Archive for November, 2012

The NE555 Timer Chip

The ‘NE555’ Timer Chip
There is an exceptionally useful chip designated by the number 555.   This chip is designed to be used in oscillator and timer circuits.   Its use is so widespread that the chip price is very low for its capability.   It can operate with voltages from 5 Volts to 18 Volts and its output can handle 200 mA.   It takes 1 mA when its output is low and 10 mA when its output is high.   It comes in an 8-pin Dual-In-Line package and there is a 14-pin package version which contains two separate 555 circuits.   The pin connections are:

This device can operate as a monostable or astable multivibrator, a Schmitt trigger or an inverting buffer (low current input, high current output).

Here it is wired as a Schmitt trigger, and for variation, it is shown triggering a triac which will then stay on until the circuit is powered down (an SCR could be used just as well with this DC circuit):

And here, a monostable:

And here are two astables, the second of which has fixed, equal mark/space ratio and the first a high output voltage time determined by Ra + Rb and a low voltage output time determined by Rb (2:1 in this case):

Note:   The high leakage of large value electrolytic capacitors prevents them being used with high value resistors in timing circuits. Instead, use a smaller capacitor and follow the timing circuit with a “divide-by-N” chip to give accurately timed long periods. Not all 555 chips have a manufacturing quality sufficient for them to operate reliably above 20,000 Hz, so for the higher frequencies the chip needs to be selected after testing its actual performance.

We can also wire the 555 to give a variable mark/space ratio while holding the frequency of the oscillation fixed:

The output waveform changes drastically as the variable resistor is adjusted, but the frequency (or pitch of the note) of the output stays unaltered.

A variable-frequency version of this circuit can be produced by changing the 33K resistor to a variable resistor as shown here:

Here, the 33K resistor has been replaced by two variable resistors and one fixed resistor.   The main variable resistor is 47K in size (an almost arbitrary choice) and it feeds to a second variable resistor of 4.7K in size.   The advantage of this second variable resistor is that it can be set to it’s mid point and the frequency tuning done with the 47K variable.   When the frequency is approximately correct, the 4.7K variable can be used to fine tune the frequency.   This is convenient as the small variable will have ten times more knob movement compared to the main variable (being just 10% of its value).

Obviously, it is not necessary to have the fine-tuning variable resistor, and it can be omitted without changing the operation of the circuit.   As the 47K variable resistor can be set to zero resistance and the 4.7K variable resistor can also be set to zero resistance, to avoid a complete short-circuit between output pin 3 and the 50K Mark/Space variable resistor, a 3.3K fixed resistor is included.   In this circuit, the frequency is set by your choice of the resistor chain 47K + 4.7K + 3.3K (adjustable from 55K to 3.3K) and the 100nF (0.1 microfarad) capacitor between pin 6 and the zero volt rail.   Making the capacitor larger, lowers the frequency range.   Making the resistors larger, also lowers the frequency range.   Naturally, reducing the size of the capacitor and/or reducing the size of the resistor chain, raises the frequency.

One 555 chip can be used to gate a second 555 chip via its pin 4 ‘Reset’ option.   You will recall that we have already developed a circuit to do this using two astables and a transistor.   We also generated the same effect using four NAND gates.   Here, we will create the same output waveform using the more conventional circuitry of two 555 chips:

Both of the 555 circuits can be bought in a single 14-pin DIL package which is designated ‘556’.

There are many additional circuit types which can be created with the 555 chip.   If you wish to explore the possibilities, I suggest that you get a copy of the book “IC 555 Projects” by E.A. Parr, ISBN 0-85934-047-3.

All right, suppose that we want to design and build a circuit to do the same as Bob Beck’s pulser circuit mentioned in chapter 11. The requirements are to produce a square wave output pulsing four times per second using a 27 volt power supply, the circuit being powered by three small PP3 size batteries. An obvious choice for the circuit seems to be a 555 timer chip which is small, robust and cheap and a suitable circuit would appear to be:

This leaves us with choosing a value for the capacitor and the resistor. We need to pay attention to the fact that the circuit will be running on 27 volts and while the capacitor will not charge up to anything like that voltage, we still will pick one which will survive 27V. Looking on the local eBay shows that a pack of ten capacitors of 1 microfarad rated at 50V can be bought for just £1 including postage, so take that as the value for “C”. Looking at the 555 table of frequencies above shows:

Which indicates that to get the circuit switching four times per second (4 Hz) the resistor “R” will need to be somewhere between 100K and 470K. With my capacitor, 120K is about right.

While the switching frequency does not have to be exact, let’s aim at getting it correct. Most reasonably priced components have a tolerance of around 10% so we need to select our resistor/capacitor combination for the exact values of the actual components which we will use. For this, it is worth building the circuit on a solder-less ‘breadboard’, so looking on eBay again we find that a suitable small plug-in board can be bought and delivered for £3. It looks like this :

These type of boards allow ICs to be plugged in spanning the central divide, leaving up to five extra connections on every pin. Short lengths of solid-core wire can be used to connect between any two socket holes. This will allow us to plug in one of our capacitors and find what resistor (or what two resistors) make the circuit switch forty times in ten seconds.

However, if we go to and download the data pdf for the NE555 chip, we find that the maximum 555 chip voltage is quite limited:

This means that the chip is liable to burn out instantly if it is fed more than 16 volts. As we need to run our circuit on 27V this is a problem. As the 27V is being provided by three separate batteries, we could supply the 555 chip from just one of the batteries and run it on 9V which would be ok from the point of view of the chip as the table above shows that it can operate correctly with a supply voltage as low as 4.5 volts. The disadvantage of that arrangement is that one of the batteries will run down more quickly than the others and it would be nice to avoid that.

The table also shows that the current draw just to keep the 555 running can be anything from 6 to 15 milliamps. That is not a large current but the PP3 batteries have been chosen for their small size, allowing the whole circuit to be strapped to a person’s wrist. A quick search on the internet shows that cheap PP3 batteries have a capacity of 400 milliamp-hours and the very expensive alkaline types 565 milliamp-hours. These ratings are the “C20” values, based on the battery being discharged at a constant current over a period of twenty hours, which would be ten days of use if Bob Beck’s two hours per day protocol is followed.

This means that the ‘cheap’ batteries should not be discharged at more than one twentieth of their 400 mAHr rating, which is 20 mA. The expensive alkaline batteries should be able to be discharged at 28 mA for twenty hours.

Our current draw is made up of two parts. The first part is supplying the circuit with the current which it needs to run. The second part is the current flowing through the body of the user. This second part is limited by the 820 ohm resistor in the output line which limits that part of the current to a maximum of 33 milliamps (Ohm’s Law: Amps = Volts /Resistance). This neglects the body resistance and assumes that the output control variable resistor is set to minimum resistance, which is unlikely.

Checking these values shows that the 555 chip is liable to draw as much current as the circuit supplies through the output electrodes. However, let’s go ahead with the circuit, after all, we might decide to use rechargeable PP3 batteries which would overcome the need to buy new batteries every few days.

The first essential requirement is to provide the 555 chip with a voltage of, say, 10 volts when it is running in the completed circuit. That could be done with one of the voltage-stabiliser integrated circuits:

That is not a particularly expensive option, but those chips draw a current in order to provide the voltage stabilisation and an absolutely steady voltage is not needed by the 555 chip. Alternatively, we could use a resistor and a 10V zener diode:

But that method does waste some current flowing through the zener in order to provide the wanted voltage. The most simple method is to use a resistor and a capacitor:

Considerable care is needed when selecting the resistor value “R”. If the value is too low, then the voltage passed to the 555 chip will be too high and the chip will burn out. When selecting the resistor “R”, start with a higher value than expected and then substitute slightly lower value resistors while monitoring the voltage across the capacitor to make sure that it stays low enough. The resistor value can be assessed using Ohm’s Law. Assuming a current of about 6 mA, the voltage drop across the resistor being (27 – 10) = 17 volts, then a resistor of about 2.83K (as Ohms = Volts / Amps) which suggests that starting with a 4.7K resistor is likely to be ok, and then picking each lower standard resistor in turn until a satisfactory voltage across the capacitor is reached.

The capacitor could be 12V or 15V rated, but if one rated at a higher voltage is used, then if it is accidentally connected across the full 27V it will not be harmed in any way. The larger the capacitance, the better, say 220 microfarads which can be got for a few pence on eBay. If you want to play safe, you could connect a 12V zener diode across the capacitor. It will not draw any current under normal working conditions, but if anything should cause the voltage on the capacitor to rise, then it will fire up and hold the voltage down to a safe 12V level. I would be inclined to see the zener as being unnecessary, but the choice is always yours.

So what resistor power rating is needed? Well, if the resistor turns out to be a 2.7K and the capacitor voltage ends up as 9.5 volts, then the average voltage across the resistor is 17.5V which makes the current through it 6.48 mA and as Watts = Volts x Amps, the power rating needs to be 113 milliwatts, so the typical quarter-watt (250 mW) resistor should be perfectly ok. If two (nearly equal value) resistors in parallel are used to get some intermediate value of “R” then that increases the overall resistor wattage.

The output of the 555 chip is then used to drive the remainder of the circuit which operates at 27V. A BC109C transistor costs only a few pence, can handle the voltage and has a minimum gain of 200 although the gain can be anything up to 800 and a BC109 can handle the current quite easily. If you need to find out any of these things, then download a datasheet for the transistor from the internet.

The output of the 555 timer is on pin 3 and it can easily supply 200 mA which is far, far more current than we would ever need for this circuit. We can feed the 555 square-wave output to the 27V electrodes using a transistor:

As the transistor is made of silicon, the switch-on voltage is when the base voltage is about 0.7 volts above the emitter voltage. That means that when the transistor is switched on, the top of resistor “R1” will be at around 10 volts and the bottom of “R1” will be at about 0.7 volts, which means that the voltage across “R1” will be (10 – 0.7) = 9.3 Volts. When that voltage is present across “R1” we want it to feed sufficient current to the transistor to switch it on fully. The transistor supplies a 100K resistor (which will carry 0.27 mA when 27 volts is across it) and the electrodes which will have a minimum resistance of 820 ohms across them (causing a current of 33 mA through them). So, the transistor might have to supply about 33 mA maximum. The BC109C transistor has a minimum gain of 200 so the current flowing into the base needs to be 33 / 200 = 0.165 mA and the resistor which will carry that current when it has 9.3 volts across it is 56.3K. A somewhat smaller resistor will suit.

A commonsense check that the resistor calculation is correct is:
A 1K resistor carries 1 mA per volt and so will carry 9.3 mA with 9.3 volts across it.
A 10K resistor will carry one tenth of that amount, or 0.93 mA with 9.3 volts across it.
A 100K resistor will carry one tenth of that again, or 0.093 mA with 9.3 volts across it.
This indicates that for a current of 0.165 mA which is about twice the 100K current, a resistor of about half of 100K should be about the right value, so 56.3K looks correct.

Considering that the gain of 200 is the minimum and three or four times that is typical, we could perhaps choose to use a 47K resistor for “R1”

As the electrode current is likely to be considerably less than 33 mA and as the BC109C gain is likely to be very high, it could be quite difficult to get the transistor to switch off as it can operate on very tiny amounts of input current. To get it to switch on and off cleanly when the 555 output voltage is say, about 5 volts, (at which point the NE555 voltage will be changing very rapidly), “R2” is included. With it in place, the output voltage of the NE555 is divided between “R1” and “R2” in the ratio of their resistances. The situation we want is:

When The transistor is not switched on, it draws almost no current and so looks like a very high value resistor to the circuit. This allows the “R1” and “R2” resistors to act as a voltage-divider pair. This causes the voltage at point “A” to be determined by the ratio of “R1” to “R2” and the transistor can be ignored provided that the voltage at point “A” is below 0.7 volts. If the voltage at that point rises to 0.7 volts then the situation changes dramatically and Ohm’s Law no longer holds as the transistor is not a passive resistor but instead, is an active semi-conductor device. If the voltage at point “A” tries to rise further it can’t because the transistor base clamps it solidly there by appearing to be an ever lower resistor between the base and the emitter of the transistor. So for higher input voltages, resistor “R2” might as well not be there for all the difference it makes.

So, what value do we need for “R2” in order for the voltage at point “A” to be 0.7V when pin 3 of the NE555 reaches 5V? Well, that part of the circuit is acting in a resistive fashion and so Ohm’s Law can be used. The resistor “R1” is 47K and has 4.3 volts across it, which means that the current through it must be 0.915 mA. That means that “R2” has 0.7V across it and 0.915 mA flowing through it which means that it has a value of 7.65K. A standard 8.2K or 6.8K resistor could be used as there is nothing dramatically important about the 5V switching point. If you were fussed about getting exactly 7.65K (and you shouldn’t be), then you can get that value by combining two standard resistors, either in series or in parallel.

A common sense method of working out the value of “R2” is to use the fact that as the same current flows through them (no matter what that current happens to be), then the ratio of the voltage will be the same as the ratio of the resistors. That is: 0.7V / 4.3V = “R2” / 47K or “R2” = 47K x 0.7 / 4.3 which is 7.65K.

We have now reached the point where we can determine the resistor value needed to provide a reasonable voltage for the NE555 timer chip, the circuit being:

The “Rx” value is going to be fairly close to 270K so you can use that value when testing to find a suitable value for “R” (2.2K in my case). The capacitor across the NE555 chip should be as large a capacitance as is convenient, bearing in mind that the entire circuit, batteries, etc. is to fit into a small case to be strapped to a wrist. One way that the components could be positioned on the plug-board is:

Remember that when trying various resistors for “R” you need to start high at about 4.7K and the resulting voltage on the capacitor shows the voltage drop across your first resistor choice and so, the actual current being drawn by your particular NE555 chip. That calculated current will allow you to calculate the resistor value needed to give 10 volts or so, allowing your next resistor to be tested to be almost exact in value.

For checking the frequency produced by the circuit, any ordinary LED can be used as a temporary measure. It can be connected across the 100K ‘load’ resistor between the transistor collector and the +27V positive supply line. A current-limiting resistor is essential to stop the LED burning out instantly. If we allow a current of 5 mA to flow through the LED then since the current-limiting resistor has some 26.3 volts across it, then it’s value will be about 5.4K (1K would give 26 mA, 2K would give 13 mA, 3K would give 9 mA, 4K would give 6.5 mA) and so a 4.7K resistor works well. This LED and resistor are shown in the layout above. Please remember that if your BC109C transistor has a metal case, then that case is normally connected internally to the collector and so, care must be taken that the case does not short-circuit to anything else.

If it is considered important to maximise battery life by reducing the current draw to a minimum, then perhaps using an astable circuit might be a good choice. In common with most electronic circuits, there are many different ways to design a suitable circuit to do the required job. The BC109C transistor can handle the 27V and so we might aim at a current draw for the circuit of just 3 mA. If 2 mA were to flow through the astable transistors when they are switched on, then with 27V across them, the resistors would be 13.5K which is not a standard value. We might select 12K to give a 2.25 mA current, or 15K to give 1.8 mA. Either should be satisfactory. The circuit might then be:

As the voltage swing feeding the output transistor has now risen from 10V to 27V the voltage-divider resistors can now increase in value by 2.7 times, giving around 127K and 22.1K for these resistors. However, the situation is not the same as for the NE555 chip which can supply at least 200 mA at the voltage-high output level. Instead, the transistor becomes such a high resistance that it can be ignored, but the 12K remains in the path which supplies the base current for the output transistor and it will in fact, add to the upper resistor of the voltage-divider pair. So while a 100K resistor is shown, it is effectively 112K due to that extra 12K resistor between it and the +27V supply line. The astable transistors will be switching fast at the point where the output transistor changes state, so the output square wave should be good quality. The BC109C transistor can switch on and off a hundred million times per second, so it’s performance in this circuit should be very good. A test breadboard layout might be:

We now need to choose the timing components. For an even 50% duty cycle where each transistor is ON for half the time and OFF for half the time, the two timing capacitors can be the same size and then the two timing resistors will have the same value, in my case, 330K but it depends on the actual capacitors used.

Bob Beck’s design calls for the LED display to be running when the unit is switched on and then be disconnected when the electrodes are plugged into a 3.5 mm socket mounted on the case containing the circuit. The switched socket looks like this:

When the plug is not inserted into the socket, pin 1 connects to pin 2 and pin 3 is not connected to anything. When the plug is inserted, then pin 1 is isolated, pin 2 is connected to plug pin 4 and pin 3 is connected to plug pin 5.

The Beck circuit is connected to the output socket like this:

This arrangement will give a 27V 4Hz square wave output through the jack socket. But, Bob Beck’s original circuit did not do that. Instead, it was like this:

Here, a relay operates two change-over switch contacts which are used to reverse the battery bank contacts four times per second. That is different from just producing a positive-going square wave voltage between the two output terminals. If you were to consider a resistor connected across the output socket, then with the relay switching, the direction of the current reverses four times per second, but with the square wave, while it starts and stops four times per second, the direction of the current is always the same and there is no reversal of direction.

As Bob wanted to avoid using a relay which clicks four times per second all the way through the two-hour treatment described in chapter 11 and in the “Take Back Your Power” pdf on the web site, he redesigned the circuit using the very impressive LM358/A integrated circuit:

This chip draws only half of one milliamp, has two very high-gain operational amplifiers and can operate with a wide range of supply voltages. It is also inexpensive.

Bob displays the circuit as:

Bob states that the first section acts as a 4Hz square-wave signal generator, the frequency being controlled by the 2.4M resistor “R1” and the 100nF capacitor “C1”. The data sheet for the LM358 states that the output voltage swing is between zero volts and 1.5V less than the supply voltage “Vcc” (which is +27V in this case). That implies that, as would be expected, the pin 1 output voltage from the first stage will switch sharply from 0V to +25.5V and sharply back again, four times per second.

It is difficult to follow the circuit as it is drawn, so it might be a little easier to follow when drawn like this:

The output from the first amplifier inside the LM358 package is on pin 1 and it can supply a large amount of current (if a large current is ever needed). That output goes straight to one of the jack socket connections. It also goes the pin 6 input of the second amplifier inside the chip and that causes the high-power output of that amplifier on pin 7 to be the opposite of the pin 1 voltage. When pin 1 goes high to +25.5 volts, then pin 7 goes low, to about zero volts. That output is also fed to the other jack socket connection, placing 25.5 volts across the electrodes when they are plugged in to the jack socket.

When the oscillator circuitry connected to the first amplifier causes the voltage on pin 1 to go low, then the output on pin 7 inverts it and so it goes to +25.5 volts. You will notice that while the overall voltage of 25.5 volts is applied again to the jack socket, the polarity is now reversed, achieving what the relay circuit does (although 1.5 volts is lost in the process). This is a neat solution.

Bob uses a two-colour LED to confirm that the circuit is working correctly before the electrodes are plugged in. He chooses to do it this way:

The two 18V zener diodes drop off 18.7 of the 25.5 volts as one will be forward biased dropping 0.7 volts and the other reversed biased, dropping off 18 volts. That leaves a 7V drop for the LED, which is a bit excessive, so Bob says that he uses a capacitor to limit the current. As there is already an 820 ohm resistor in the LED current path through the socket, the capacitor is not needed. The variable resistor need to be set to it’s minimum resistance by rotating it’s shaft fully clockwise so that it does not affect the LED brightness as the zeners also show when the battery voltage has dropped as there will no longer be sufficient voltage to light the LED brightly, indicating that the batteries need to be replaced (or recharged if they are rechargeable batteries). When testing the circuit, an alternative to the two zeners is to use a 4.7K resistor and if a bi-colour LED is not to hand, then two ordinary LEDs can be used back to back like this:

With this arrangement, the two LEDs flash alternately. In any circuit, a capacitor with a higher voltage rating can always be used if the capacitance values are the same. The Beck external circuit is completed through the body of the user, so there is just one electrode connected to each side of the output jack socket. A possible plug-board layout is:

The 4.7K resistor and LEDs are only on the board for testing purposes and when the circuit is built in permanent form, then the LED chain connects to pin 1 of the jack socket so that the LEDs are disconnected during the two hours of daily treatment recommended when using the device.

One stripboard layout using the standard 9-strip 25-hole board and incorporating the two 18V zener diodes for voltage sensing is:

When using a Beck device, it is very important to pay attention to the precautions which Bob sets out. These are in his “Take Back Your Power” pdf document: which includes the following, which, while it refers to treatment to deal with HIV, presumably applies to all treatments with his device:


HYPOTHETICAL PROTOCOLS FOR EXPERIMENTAL SESSIONS Revision March 20, 1997. Copyright 8 1991/1997 Robert C. Beck

PRECAUTIONS: Do NOT use wrist to wrist current flow with subjects who have cardiac pacemakers. Any applied electrical signals may Interfere with ‘demand’ type heart pacers and cause malfunction. Single wrist locations should be acceptable. Do NOT use on pregnant women, while driving or using hazardous machinery.

Users MUST avoid Ingesting anything containing medicinal herbs, foreign or domestic, or potentially toxic medication. nicotine, alcohol, recreational drugs. laxatives, tonics. and certain vitamins etc., for one week before starting because blood electrification can cause electroporation which makes cell membranes pervious to small quantities of normally harmless-chemicals in plasma. The effect Is the same as extreme overdosing which might be lethal. See Electroporation: a General Phenomenon for Manipulating Cells and Tissues; J.C. Weaver, Journal of Cellular Biochemistry 51:426-435 (1993). Effects can mimic increasing dosages many fold. Both the magnetic pulsar and blood purifier cause electroporation.

Do NOT place electrode pads over skin lesions, abrasions, new scars, cuts, eruptions, or sunburn. Do NOT advance output amplitude to uncomfortable levels. All subjects will vary. Do NOT fall asleep while using. The magnetic pulser should be safe to use anywhere on body or head.

Avoid ingesting alcohol 24 hours before using. Drink an 8 oz. glass of distilled water 15 minutes before and immediately following each session end drink at least four additional glasses daily for flushing during ‘neutralization’ and for one week thereafter. This Is imperative. Ignoring this can cause systemic damage from unflushed toxic wastes. When absolutely essential drugs must be ingested, do so a few minutes after electrification then wait 24 hours before next session.

If subject feels sluggish, faint, dizzy, headachy, light-headed or giddy, nauseous. bloated or has flu-like symptoms or rashes after exposures, reduce pulsing per session and/or shorten applications of electrification. Drink more water-preferably ozonized -to speed waste oxidation and disposal. Use extreme caution when treating patients with impaired kidney or liver function. Start slowly at first like about 20 minutes per day to reduce detoxification problems.

To avoid shock liability, use batteries only. Do NOT use any line-connected power supply, transformer, charger, battery eliminator, etc. with blood clearing device. However line supplies are OK with well-insulated magnetic pulse generators (strobe lights).

Health professionals: Avoid nicotine addicts, vegans, and other unconsciously motivated death-wishers and their covert agendas of ‘defeat the healer’. Tobacco, the most addictive (42times more addictive than heroin) and deadly substance of abuse known, disrupts normal cardiovascular function. True vegetarian diets are missing essential amino acids absolutely necessary for the successful rebuilding of AlDS-ravaged tissues. Secondary gains (sympathy / martyrdom, work avoidance, free benefits, financial assistance, etc.) play large roles with many AIDS patients. “Recovery guilt” as friends are dying has even precipitated suicide attempts masked as ‘accidents’. Avoid such entanglements, since many have unconscious death wishes.

SUPERIOR ELECTRODES: Excellent, convenient and vastly superior electrodes, reusable indefinitely can be made by butt-soldering lead wires to ends of 1” long by 3/32” dia. blanks cut from type 316 stainless steel rods available from welding supply stores (Cameron Welding Supply. 11061 Dale Ave., Stanton, CA 90680). Use ‘Stay Clean’ flux before soldering (zinc chloride/hydrochloric acid). Shrink-insulate TWO tight layers of tubing over soldered joints to prevent flexing/breaking and lead/copper ions from migrating. Wrap three or four turns of 100% cotton flannel around rods. Spiral-wrap with strong thread starting from wire side to end, tightly pinch cloth over the rod’s end so as to leave no metal exposed by wrapping 6 or 7 turns of thread TIGHTLY just off end of rod, then spiral wrap back to start and tie tightly with four knots then cut off excess cloth at end close to pinch -wraps. Treat end windings and knots with clear fingernail polish or Fray Check® (fabric & sewing supply stores) to prevent ravelling. Soak in a strong solution of sea salt (not table salt) containing a little wetting agent like Kodak Photo Flow, ethylene glycol, or 409 kitchen cleaner. Add a few drops of household bleach, sliver colloid, etc., for disinfectant. Store solution for reuse. Tape soaking-wet electrodes tightly over pulse sites with paper masking or Transpore™ tape or with 1”wide stretch elastic bands with tabs of Velcro ® at ends to fasten. Electrodes should closely conform precisely along blood vessels, not skewing ever so slightly over adjacent flesh. This insures better electrical conductivity paths to circulating blood and insures very low internal impedance. (~2000W). Rinse and blot-dry electrodes and skin after each use. NEVER allow bare metal to touch skin as this will cause burns manifested as small red craters that heal slowly. The objective is to get maximum current into blood vessels, not leak it over to adjacent tissue. Therefore never use any electrode wider that about 1/8 inch (3 mm).

ELECTRODE PLACEMENTS: Locate maximum pulse position (NOT to be confused with acupuncture, reflexology, Chapman, etc. points) on feet or wrists by feeling for maximum pulse on inside of ankle about 1”below and to rear of ankle bone, then test along top centre of instep. Place electrode on whichever pulse site on that foot that feels strongest. Scrub skin over chosen sites with mild soap and water or alcohol swab. Wipe dry. Position the electrodes lengthwise along each left and right wrists blood vessel. Note: with subjects having perfectly healthy hearts and not wearing pacers, it is convenient to use left wrist to right wrist exactly over ulnar arterial pulse paths instead of on feet. Recent (Dec. 1995) research suggests that placing both electrodes over different arteries on the same wrist works very well (see pg. 7), avoids any current through heart, and is much more convenient and just as effective. An 8” long, 1” wide elastic stretch-band with two 1.5” lengths of 3/4” wide Velcro ® sewn to ends of opposite sides makes an excellent wrist band for holding electrodes snugly in place. With electrode cable unplugged, turn switch ON and advance amplitude control to maximum. Push momentary SW. 2 ‘Test’ switch and see that the red and green light emitting diodes flash alternately. This verifies that polarity is reversing about 4 times per second (frequency is NOT critical) and that batteries are still good. When LED’s don’t light replace all three 9V batteries. Zener diodes will extinguish the LEDs when the three 9V battery’s initial 27V drops below 18V after extended use. Never use any electrode larger than 1.125” (28 mm) long by 1/8” wide to avoid wasting current through surrounding tissue. Confine exactly over blood vessels only. Apply drops of salt water to each electrode’s cotton cover ~every 20 minutes to combat evaporation and insure optimum current flow. Later devices are solid-state, use only three batteries and no relays, and are much smaller.

Now rotate amplitude control to minimum (counter-clockwise) and plug In electrode cable. Subject now advances dial slowly until he feels a “thumping” and tingling. Turn as high as tolerable but don’t advance amplitude to where It is ever uncomfortable. Adjust voltage periodically as he adapts or acclimates to current level after several minutes. If subject perspires, skin resistance may decrease because of moisture, so setting to a lower voltage for comfort is indicated. Otherwise it is normal to feel progressively less sensation with time. You may notice little or no sensation at full amplitude immediately, but feeling will begin building up to maximum after several minutes at which time amplitude must be decreased. Typical adapted electrode-to-electrode impedance is on the order of 2000W. Typical comfortable input (to skin) is ~3mA, and maximum tolerable input (full amplitude) is about7mA but this ‘reserve’ margin although harmless is unnecessary and can be uncomfortable. Current flowing through blood Is very much lower than this external input because of series resistance through skin, tissue and blood vessel walls, but 50 to 100 µA through blood is essential.

Apply blood neutralizer for about 2 hours daily for about2 months. Use judgment here. The limiting factor is detoxification. Carefully monitor subject’s reactions (discomfort, catarrh, skin eruptions, weeping exudites, rashes, boils, carbuncles, coated tongue, etc.). With very heavy infections, go slower so as not to overload body’s toxic disposal capability. With circulation-impaired diabetics, etc., you may wish to extend session times. Again, have subject drink lots of water. Recent changes in theoretical protocol being currently tested suggest following up the three weeks of treatments with a 24 hours per day (around the clock) continuous electrification of blood for two days to deal a knockout blow to the remaining HIV ’s 1.2 day life cycle. (A. Perelson; Los Alamos Biophysics Group, Mar. 16, 1996 “Science” Journal.) Remember to remoisten electrodes regularly. If you absolutely must ingest prescription drugs, do so immediately after turning off instrument and allow 24 hours before next treatment to let concentrations in blood plasma decay to lower levels.

Remember, if subjects ever feel sleepy, sluggish, listless. nauseous, faint, bloated, or headachy, or have flu-like reactions they may be neglecting sufficient water intake for flushing toxins. We interpret this as detoxification plus endorphin release due to electrification. Let them rest and stabilize for about 45 minutes before driving if indicated. If this detoxing becomes oppressive, treat every second day. Treating at least 21 times should ‘fractionate’ both juvenile and maturing HIV to overlap maximum neutralization sensitivity windows and interrupt ‘budding’ occurring during HIV cells’ development cycles. Treatments are claimed to safely neutralize many other viruses, fungi, bacteria, parasites, and microbes in blood. See patents US 5,091,152 US 5,139,684 US 5,188,738 US 5,328,451 and others as well as numerous valid medical studies which are presently little known or suppressed. Also. ingesting a few oz. of about 5 parts per million of silver colloid solution daily can give subjects a ‘second intact immune system’ and minimise or eliminate opportunistic infections during recovery phase. This miracle substance Is pre-1938 technology, and unlike ozone is considered immune from FDA harassment. Silver colloid can easily be made at home electrolytically in minutes and in any desired quantities and parts per million strength for under 14 cents per gallon plus cost of water. It is ridiculous to purchase it for high prices. Colloid has no side effects, and is known to rapidly eliminate or prevent hundreds of diseases. Sliver colloids won’t produce drug resistant strains as will all other known antibiotics. No reasonable amount can overdose or injure users either topically, by ingestion, or medical professional injection.

Electronics Tutorial

Gate Circuits

Gate Circuits
NAND Gates can be used as the heart of many electronic circuits apart from the logic circuits for which the package was designed.   Here is a NAND gate version of the rain alarm described earlier.   The ‘4011B’ chip is a CMOS device which has a very high input impedance and can operate at convenient battery voltages (3 to 15 Volts):

This circuit is comprised of a rain sensor, two astable multivibrators and a power-driver feeding a loudspeaker:

    1. The rain sensor is a wired-up strip board or similar grid of interlaced conductors, forming a voltage-divider across the battery rails.
    1. The output voltage from this, at point ‘A’ in the circuit diagram, is normally low as the strip board is open-circuit when dry.   This holds the first NAND gate locked in the OFF state, preventing the first astable from oscillating.   This first astable is colour-coded blue in the diagram.   Its frequency (the pitch of the note it produces) is governed by the values of the 47K resistor and the 1 microfarad capacitor.   Reducing the value of either of these will raise the frequency (note pitch).   If rain falls on the sensor, the voltage at point ‘A’ goes high letting the astable run freely.   If the voltage at ‘A’ does not rise sufficiently when it rains, increase the value of the 1M resistor.
    1. The output of the first astable is a low voltage when the sensor is dry.   It is taken from point ‘B’ and passed to the gating input of the second astable, holding it in its OFF state.   The speed of the second astable is controlled by the value of the 470K resistor and the 0.001 microfarad capacitor.   Reducing the value of either of these will raise the pitch of the note produced by the astable.   The rate at which this astable operates is very much higher than the first astable.
      When it starts to rain, the voltage at point ‘


      ’ rises, letting the first astable oscillate.   As it does so, it turns the second astable on and off in a steady rhythmic pattern.   This feeds repeated bursts of high speed oscillations from the second astable to point ‘


      ’ in the diagram.
  1. The Darlington-pair emitter-follower transistors cause the voltage at point ‘D’ to follow the voltage pattern at point ‘C’ (but 1.4 Volts lower voltage due to the 0.7 Volts base/emitter voltage drop for each transistor).   The high gain of the two transistors ensures that the output of the second oscillator is not loaded unduly.   These power-driver transistors place the output voltage across an eighty ohm loudspeaker, padded with a resistor to raise the overall resistance of the combination.   The voltage pattern produced is shown at point ‘D’ and is an attention-grabbing sound.


So, why does this circuit oscillate?:

The circuit will not oscillate if the gating input is low, so assume it to be high.   Take the moment when the output of gate 2 is low.   For this to happen, the inputs of gate 2 have to be high.   As the output of gate 1 is wired directly to the inputs of gate 2, it must be high, and for that to be true, at least one of its inputs must be low.   This situation is shown on the right.

There is now a full voltage drop between point ‘A’ and point ‘B’.   The 47K resistor and the capacitor are in series across this voltage drop, so the capacitor starts to charge up, progressively raising the voltage at point ‘C’.   The lower the value of the resistor, the faster the voltage rises.   The larger the value of the capacitor, the slower the voltage rises.

When the voltage at point ‘C’ rises sufficiently, the 100K resistor raises the input voltage of gate 1 far enough to cause it to change state.   This creates the following situation:

Now, the voltage across ‘A’ to ‘B’ is reversed and the voltage at point ‘C’ starts to fall, its rate governed by the size of the 47K resistor and the 1 microfarad capacitor.   When the voltage at point ‘C’ falls low enough, it takes the input of gate 1 low enough (via the 100K resistor) to cause gate 1 to switch state again.   This takes the circuit to the initial state discussed.   This is why the circuit oscillates continuously until the gating input of gate 1 is taken low to block the oscillation.

Now, here is a NAND gate circuit for a sequential on/off switch:

This circuit turns the Light Emitting Diode on and off repeatedly with each operation of the press-button switch.   When the on/off switch is closed, capacitor ‘C1’ holds the voltage at point ‘A’ low.   This drives the output of gate 1 high, which moves the inputs of gate 2 high via the 100K resistor ‘R1’.   This drives the voltage at point ‘B’ low, turning the transistor off, which makes the LED stay in its off state.   The low voltage at point ‘B’ is fed back via the 100K resistor ‘R2’ to point ‘A’, keeping it low.   This is the first stable state.

As the output of gate 1 is high, capacitor ‘C2’ charges up to that voltage via the 2M2 resistor.   If the press-button switch is operated briefly, the high voltage of ‘C2’ raises the voltage of point ‘A’, causing gate 1 to change state, and consequently, gate 2 to change state also.   Again, the high voltage at point ‘B’ is fed back to point ‘A’ via the 100K resistor ‘R2’, keeping it high, maintaining the situation.   This is the second stable state.   In this state, point ‘B’ has a high voltage and this feeds the base of the transistor via the 4.7K resistor, turning it on and lighting the LED.

In this second state, the output of gate 1 is low, so capacitor ‘C2’ discharges rapidly to a low voltage.   If the press-button switch is operated again, the low voltage of ‘C2’ drives point ‘A’ low again, causing the circuit to revert to its original stable state.

We could, if we wished, modify the circuit so that it would operate for three or four minutes after switch-on but then stop operating until the circuit was turned off and on again.   This is accomplished by gating one of the gates instead of just using both as inverters.   If we gated the second gate, then the LED would be left permanently on, so we will modify the first gate circuit:

This circuit operates exactly the same way as the previous circuit if, and only if, the voltage at point ‘C’ is high.   With the voltage at point ‘C’ high, gate 1 is free to react to the voltage at point ‘A’ as before.   If the voltage at point ‘C’ is low, it locks the output of gate 1 at the high level, forcing the output of gate 2 to the low level and holding the LED off.

When the circuit is first powered up, the new 100 microfarad capacitor ‘C3’ is fully discharged, which pulls the voltage at point ‘C’ to nearly + 9 Volts.   This allows gate 1 to operate freely, and the LED can be toggled on and off as before.   As time passes, the charge on capacitor ‘C3’ builds up, fed by the 2M2 resistor.   This causes the voltage at point ‘C’ to fall steadily.   The rate of fall is governed by the size of the capacitor and the size of the resistor.   The larger the resistor, the slower the fall.   The larger the capacitor, the slower the fall.   The values shown are about as large as are practical, due to the current ‘leakage’ of ‘C3’.

After three or four minutes, the voltage at point ‘C’ gets driven low enough to operate gate 1 and prevent further operation of the circuit.   This type of circuit could be part of a competitive game where the contestants have a limited time to complete some task.

Gates can also be used as amplifiers although they are not intended to be used that way and there are far better integrated circuits from which to build amplifiers.   The following circuit shows how this can be done:

This circuit operates when there is a sudden change in light level.   The previous light-level switching circuit was designed to trigger at some particular level of increasing or decreasing level of lighting.   This is a shadow-detecting circuit which could be used to detect somebody walking past a light in a corridor or some similar situation.

The voltage level at point ‘A’ takes up some value depending on the light level.   We are not particularly interested in this voltage level since it is blocked from the following circuitry by capacitor ‘C1’.   Point ‘B’ does not get a voltage pulse unless there is a sudden change of voltage at point ‘A’, i.e. there is a sudden change in light level reaching the light-dependent resistor ORP12.

The first gate amplifies this pulse by some fifty times.   The gate is effectively abused, and forced to operate as an amplifier by the 10M resistor connecting its output to its input.   At switch-on, the output of gate 1 tries to go low.   As its voltage drops, it starts to take its own inputs down via the resistor.   Pushing the voltage on the inputs down, starts to raise the output voltage, which starts to raise the input voltage, which starts to lower the output voltage, which ……   The result is that both the inputs and the output take up some intermediate voltage (which the chip designers did not intend).   This intermediate voltage level is easily upset by an external pulse such as that produced by the ORP12 through capacitor ‘C1’.   When this pulse arrives, an amplified version of the pulse causes a voltage fluctuation at the output of gate 1.

This voltage change is passed through the diode and variable resistor to the input of gate 2.   Gates 2 and 3 are wired together as a makeshift Schmitt trigger in that the output voltage at point ‘D’ is fed back to point ‘C’ via a high value resistor.   This helps to make their change of state more rapid and decisive.   These two gates are used to pass a full change of state to the output stage transistor.   The variable resistor is adjusted so that gate 2 is just about to change state and is easily triggered by the pulse from amplifier gate 1.   The output is shown as an LED but it can be anything you choose.   It could be a relay used to switch on some electrical device, a solenoid used to open a door, a counter to keep track of the number of people using a passageway, etc. etc.   Please note that an operational amplifier chip (which will be described later) is a far better choice of IC for a circuit of this type.   A gate amplifier is shown here only to show another way that a gate can be utilised.

Electronics Tutorial


Consider the following circuit:

If neither of the press-button switches are operated, the transistor has no base/emitter current flow and so it is off.   This places the collector voltage at ‘C’ near the positive rail (+5 Volts).

If press-button switch ‘A’ is operated, the base voltage tries to rise to half of the battery voltage but doesn’t make it because the transistor base pins it down to 0.7 Volts. This feeds base current to the transistor, switching it hard on and causing the output at ‘C’ to drop to nearly 0 Volts.

If press-button switch ‘B’ is operated (don’t do this when switch ‘A’ is closed or you will get a very high ‘short-circuit’ current flowing directly through the two switches) it has no effect on the output voltage which will stay high.

If we re-draw the circuit like this:

We can see that if the voltage at the input ‘A’ is taken high, then the output voltage at ‘C’ will be low. If the voltage at the input ‘A’ is taken low, then the output voltage at ‘C’ will be high. A circuit which does this is called an ‘Inverter’ because it ‘inverts’ (or ‘turns upside down’) the input voltage.

We can summarise this operation in a table.   Personally, I would call the table an ‘Input/Output’ table, but for no obvious reason, the standard name is a ‘Truth’ table.   The purpose of this table is to list all of the possible inputs and show the corresponding output for each input.

Another standard, is to substitute ‘1’ for ‘High Voltage’ and ‘0’ for ‘Low Voltage’.   You will notice that many items of electrical and electronic equipment have these symbols on the ON / OFF switch.   In computer circuitry (hah! you didn’t notice that we had moved to computer circuits, did you?), the ‘0’ represents any voltage below 0.5 Volts and the ‘1’ represents any voltage above 3.5 Volts.   Many, if not most, computers operate their logic circuits on 5 Volts.   This Inverter circuit is a ‘logic’ circuit.

A criticism of the above circuit is that its input resistance or ‘impedance’ is not particularly high, and its output impedance is not particularly low.   We would like our logic circuits to be able to operate the inputs of eight other logic circuits.   The jargon for this is that our circuit should have a ‘fan-out’ of eight.

Let’s go for a simple modification which will improve the situation:

Here, The input impedance has been increased by a factor of 100 by using a Darlington pair of transistors which need far less base current, and so can have a much higher input resistor.

Unfortunately, the output impedance is still rather high when the transistors are in their OFF state as any current taken from the positive line has to flow through the 1K8 (1800 ohm) resistor.   But we need this resistor for when the transistors are in their ON state.   We really need to change the 1K8 resistor for some device which has a high resistance at some times and a low resistance at other times.   You probably have not heard of these devices, but they are called ‘transistors’.

There are several ways to do this.   We might choose to use PNP transistors (we normally use NPN types) and connect these in place of the 1K8 resistor.   Perhaps we might use a circuit like this:

This circuit is starting to look complicated and I don’t like complicated circuits.   It is not as bad as it looks.   The NPN transistors at the bottom are almost the same as the previous circuit.   The only difference is that the collector load is now two 100 ohm resistors plus the resistance of the two transistors.   If the PNP transistors are OFF when the NPN transistors are ON, then the circuit loading on the NPN transistors will be negligible and the whole of the NPN transistors output will be available for driving external circuits through the lower 100 ohm resistor (a large ‘fan-out’ for the ‘0’ logic state).   To make sure that the PNP transistors are hard off before the NPN transistors start to switch on, the resistor ‘R1’ needs to be selected carefully.

The PNP transistors are an exact mirror image of the NPN side, so resistor ‘R2‘ needs to be selected carefully to ensure that the NPN transistors are switched hard OFF before the PNP transistors start to switch ON.

You need not concern yourself unduly with that circuit, because you will almost certainly use an Integrated Circuit rather than building your own circuit from ‘discrete’ components.  An Integrated Circuit containing six complete inverters is the 7414 which is shown above.   This comes in a small black case with two rows of 7 pins which make it look a bit like a caterpillar.   Because there are two row of pins, the packaging is called “Dual In-Line” or “DIL” for short.

Now, consider the following circuit:

This circuit operates the same way as the Inverter circuit, except that it has two inputs (‘A’ and ‘B’). The output voltage at ‘C’ will be low if either, ‘AORB’ or both, of the inputs is high. The only time that the output is high, is when both Input ‘A’ and Input ‘B’ are low. Consequently, the circuit is called an “OR” gate. Strictly speaking, because the output voltage goes Down when the input voltage goes Up, it is called a “Not OR” gate, which gets shortened to a “NOR” gate. In this context, the word “not” means “inverted”. If you fed the output ‘C’ into an inverter circuit, the resulting circuit would be a genuine “OR” gate. The digital circuit symbols for an AND gate, a NAND gate, an OR gate and a NOR gate are:

These common chips are usually supplied with 2, 4 or 8 inputs.  So, why is it called a “Gate” – isn’t it just a double inverter?   Well, yes, it is a double inverter, but a double inverter acts as a gate which can pass or block an electronic signal.   Consider this circuit:

Here, transistors ‘TR1’ and ‘TR2’ are connected to form an astable (multivibrator).   The astable runs freely, producing the square wave voltage pattern shown in red.   Transistor ‘TR3’ passes this voltage signal on.   TR3 inverts the square wave, but this has no practical effect, the output being the same frequency square wave as the signal taken from the collector of TR2.

If the press-button switch at point ‘A’ is operated, a current is fed to the base of TR3 which holds it hard on.   The voltage at point ‘C’ drops to zero and stays there.   The square wave signal coming from the collector of TR2 is blocked and does not reach the output point ‘C’.   It is as if a physical ‘gate’ has been closed, blocking the signal from reaching point ‘C’.   As long as the voltage at point ‘A’ is low, the gate is open.   If the voltage at point ‘A’ goes high, the gate is closed and the output is blocked.

There is no need for a manual switch at point ‘A’.   Any electronic switching circuit will do:

Here, a slow-running astable is substituted for the manual switch.   When the output voltage of ‘Astable 2’ goes high, it switches the gate transistor ‘TR3’, holding it hard on and blocking the square-wave signal from ‘Astable 1’.   When the output voltage of ‘Astable 2’ goes low, it frees transistor ‘TR3’ and it then passes the ‘Astable 1’ signal through again.   The resulting gated waveform is shown in red at point ‘C’ and it is bursts of signal, controlled by the running rate of ‘Astable 2’.   This is the sort of waveform which Stan Meyer found very effective in splitting water into Hydrogen and Oxygen (see Chapter 10).

This circuit could also be drawn as:

The small circle on the output side of logic devices is to show that they are inverting circuits, in other words, when the input goes up, the output goes down.   The two logic devices we have encountered so far have had this circle: the Inverter and the NAND gate.

If you wish, you can use a NAND gate chip which has the circuitry also built as a Schmitt trigger, which as you will recall, has a fast-switching output even with a slowly moving input.   With a chip like that, you can get three different functions from the one device:

If the two inputs of a NAND gate are connected together, then the output will always be the opposite of the input, i.e. the gate acts as an inverter.   This arrangement also works as a Schmitt Trigger due to the way the NAND gate circuitry is built.   There are several packages built with this type of circuitry, the one shown here is the “74132” chip which contains four “dual-input” NAND gates.   Gates can have almost any number of inputs but it is rare to need more than two in any given circuit.   Another chip with identical pin connections is the 4011 chip (which is not a Schmitt circuit).   This ‘quad dual-input’ NAND gate package uses a construction method called “CMOS” which is very easily damaged by static electricity until actually connected into a circuit.   CMOS chips can use a wide range of voltages and take very little current.   They are cheap and very popular

The number of devices built into an Integrated Circuit is usually limited by the number of pins in the package and one pin is needed for one connection to ‘the outside world’.   Packages are made with 6 pins (typically for opto-isolators), 8 pins (many general circuits), 14 pins (many general circuits, mostly computer logic circuits), 16 pins (ditto, but not as common) and then a jump to large numbers of pins for Large Scale devices such as microprocessors, memory chips, etc.   The standard IC package is small:

Prototype circuits are often built on ‘strip board’ which is a stiff board with strips of copper running along one face, and punched with a matrix of holes.   The strips are used to make the electrical connections and are broken where necessary.   This strip board is usually called “Veroboard”:

Nowadays, the strip board holes are spaced 2.5 mm (1/10”) apart which means that the gaps between the copper strips is very small indeed.   I personally, find it quite difficult to make good solder joints on the strips without the solder bridging between two adjacent strips.   Probably, a smaller soldering iron is needed.   I need to use an 8x magnifying glass to be sure that no solder bridging remains in place before a new circuit is powered up for the first time.   Small fingers and good eyesight are a decided advantage for circuit board construction.   The narrow spacing of the holes is so that the standard IC DIL package will fit directly on the board.

Circuits built using computer circuitry, can experience problems with mechanical switches.   An ordinary light switch turns the light on and off.   You switch it on and the light comes on.   You switch it off and the light goes off.   The reason it works so well is that the light bulb takes maybe, a tenth of a second to come on.   Computer circuits can switch on and off 100,000 times in that tenth of a second, so some circuits will not work reliably with a mechanical switch.   This is because the switch contact bounces when it closes.   It may bounce once, twice or several times depending on how the switch is operated.   If the switch is being used as an input to a counting circuit, the circuit may count 1, 2 or several switch inputs for one operation of the switch.   It is normal to “de-bounce” any mechanical switch.   This could be done using a couple of NAND gates connected like this:

Here, the mechanical switch is buffered by a ‘latch’.   When the ‘Set’ switch is operated, the output goes low.   The unconnected input of gate ‘1’ acts as if it has a High voltage on it (due to the way the NAND gate circuit was built).   The other input is held low by the output of gate ‘2’.   This pushes the output of gate ‘1’ high, which in turn, holds the output of gate ‘2’ low.   This is the first stable state.

When the ‘Set’ switch is operated, the output of gate ‘2’ is driven high.   Now, both inputs of gate ‘1’ are high which causes its output to go low.   This in turn, drives one input of gate ‘2’ low, which holds the output of gate ‘2’ high.   This is the second stable state.

To summarise: pressing the ‘Set’ switch any number of times, causes the output to go low, once and only once.   The output will stay low until the ‘Reset’ switch is operated once, twice or any number of times, at which point the output will go high and stay there.

This circuit uses just half of one cheap NAND gate chip to create a bistable multivibrator which is physically very small and light.

Electronics Tutorials


The number of electronic circuits which can be built with basic components such as resistors, capacitors, transistors, coils, etc. is limited only by your imagination and needs.   Here is a circuit where two transistors operate as a pair:

This circuit has two stable states and so it is called a “bi” “stable” or “bistable” circuit.  It is important to understand the operation of this simple and useful circuit.

If press-button switch ‘A’ is pressed, it short-circuits the base/emitter junction of transistor TR1.   This prevents any current flowing in the base/emitter junction and so switches TR1 hard off.   This makes the voltage at point ‘C’ rise as high as it can. This leaves transistor TR2 powered by R1 and R2 which have 11.3 Volts across them and switches TR2 hard on.

This pulls point ‘D’ down to about 0.1 Volts.   This happens in less than a millionth of a second.   When the press-button switch ‘A’ is released, transistor TR1 does not switch on again because its base current flows through resistor R3 which is connected to point ‘D’ which is far, far below the 0.7 volts needed to make TR1 start conducting.

The result is that when press-button ‘A’ is pressed, transistor TR2 switches on and stays on even when press-button ‘A’ is released.   This switches transistor TR3 off and starves the Load of current.   This is the first ‘stable state’.

The same thing happens when press-button ‘B’ is pressed.   This forces transistor TR2 into its ‘off’ state, raising point ‘D’ to a high voltage, switching transistor TR3 hard on, powering the Load and holding transistor TR1 hard off.   This is the second of the two ‘stable states’.

In effect, this circuit ‘remembers’ which press-button was pressed last, so millions of these circuits are used in computers as Random Access Memory (‘RAM’).   The voltage at point ‘C’ is the inverse of the voltage at point ‘D’, so if ‘D’ goes high then ‘C’ goes low and if ‘D’ goes low, then ‘C’ goes high.   In passing, the output at ‘D’ is often called ‘Q’ and the output at ‘C’ is called ‘Q-bar’ which is shown as the letter Q with a horizontal line drawn above it.   This is shown on the next circuit diagram.

A minor variation of this circuit allows a load to be energised when the circuit is powered up:

When powered down, the capacitor ‘C1’ in this circuit is fully discharged through resistor ‘R6’.   When the 12 Volts supply is connected to the circuit, capacitor C1 does not charge instantly and so holds the base of TR2 down below 0.7 Volts for much longer than it takes for transistor TR1 to switch on (which, in turn, holds TR2 hard off).   Mind you, if it is not necessary to have the Load held powered on indefinitely, then an even more simple circuit can do this:

Here, when the switch is closed, both sides of the capacitor C1 are at +12 Volts and this causes the 1K8 resistor to conduct heavily, driving the transistor and powering the load.   The capacitor charges rapidly through the transistor and reaches the point at which it can no longer keep the transistor switched on.   When the battery is switched off, the 1M resistor discharges the capacitor, ready for the next time the battery is connected.

The Monostable Multivibrator.
The monostable has one stable state and one unstable state.   It can be flipped out of its stable state but it will ‘flop’ back into its stable state.   For that reason, it is also known as a ‘flip-flop’ circuit.   It is similar to a bistable circuit, but one of the cross-link resistors has been replaced by a capacitor which can pass current like a resistor, but only for a limited amount of time, after which, the capacitor becomes fully charged and the current flow stops, causing the ‘flop’ back to the stable state once more.

In this circuit, the ‘R’ resistor and the ‘C’ capacitor values determine how long the monostable will be in its unstable state.   The circuit operates like this:

    1. In the stable state, transistor TR1 is off. Its collector voltage is high, pushing the left hand side of capacitor ‘C’ to near +12 Volts.   As the right hand side of capacitor ‘C’ is connected to the base of TR2 which is at 0.7 Volts, the capacitor gets charged to about 11.3 Volts.
    1. The press-button switch is operated briefly.   This feeds current through its 10K resistor to the base of transistor TR1, switching it hard on.   This drops the collector voltage of TR1 to near 0 Volts, taking the left hand side of the capacitor with it.
    1. As the voltage across a capacitor can’t change instantly, the right hand side of the capacitor drives the base of transistor TR2 down below 0.7 Volts, causing TR2 to switch off.
  1. The circuit can’t hold TR2 in its ‘off’ state for ever.   The resistor ‘R’ feeds current into the capacitor, forcing the voltage at the base of TR2 steadily upwards until the voltage reaches 0.7 Volts and transistor TR2 switches on again, forcing TR1 off again (provided that the press-button switch has been released).   This is the stable state again.   If the press-button switch is held on, then both transistors will be on and the output voltage will still be low.   Another output pulse will not be generated until the press-button is let up and pressed again.

This circuit could be used to switch a microwave oven on for any chosen number of seconds, create a delay on your home-built burglar alarm, to give you time to switch it off after walking through your front door, operate a solenoid valve to feed a pre-determined quantity of beverage into a bottle on a production line, or whatever…

The Astable multivibrator.
The astable circuit is the monostable with a second capacitor added so that neither state is stable.   This results in the circuit flopping backwards and forwards continuously:

The rate of switching is controlled by the R1/C1 and R2/C2 combinations.   The load’s ON time to its OFF time is called the ‘mark-space’ ratio, where the ON period is the ‘mark’ and the OFF period is the ‘space’.   If you choose to use electrolytic capacitors which have their own polarity, then the +ve end of each capacitor is connected to the transistor collector.

While it is good to understand how these multivibrator circuits operate and can be built, nowadays there are pre-built circuits encased in a single package which you are much more likely to choose to use.   These are called Integrated Circuits or ‘ICs’ for short.   We will be discussing these shortly.   Before we do, notice that in the circuit above, transistor TR3 has been changed to a new variety called a Field Effect Transistor (‘FET’).   This type of transistor is newer than the ‘bipolar’ transistors shown in the earlier circuits.   FETs come in two varieties: ‘n-channel’ which are like NPN transistors and ‘p-channel’ which are like PNP transistors.

FETs are more difficult to make but have now reached a level of cost and reliability which makes them very useful indeed.   They require almost no base current (called ‘gate’ current with this type of transistor) which means that they have almost no effect on any circuit to which they are attached.   Also, many of them can handle large currents and boast major power handling capabilities.   Because of this, it is usual to see them packaged with a metal plate mounting, ready to be bolted to an aluminium heat-sink plate to help dissipate the heat generated by the large amount of power flowing through them.   The ‘RFP50N06’ shown above can handle up to 50 Volts and carry up to 60 Amps, which is serious power handling.

Electronics Tutorial

The Voltage Doubler

The Voltage Doubler
It is possible to increase the output voltage of a transformer although this does reduce its ability to supply current at that voltage. The way that this is done is to feed the positive cycles into one storage capacitor and the negative cycles into a second reservoir capacitor. This may sound a little complicated, but in reality, it isn’t. A circuit for doing this is shown here:

With this circuit, the transformer output is some voltage, say “V” volts of AC current. This output waveform is fed to capacitor “C1” through diode “D1” which lops off the negative part of the cycle. This produces a series of positive half-cycles which charge up capacitor “C1” with a positive voltage of “V”.

The other half of the output is fed to capacitor “C2” through diode “D2” which cuts off the positive part of the cycle, causing capacitor “C2” to develop a voltage of -V across it. As the two capacitors are ‘in series’ and not placed across each other, their voltages add up and produce twice the transformer output voltage.

A word of warning here. The transformer is producing an AC waveform and these are marked with the average voltage of the waveform, which is usually a sine wave. The peak voltage of a sinewave is 41% greater than this, so if your transformer has an AC output of 10 volts, then the peaks fed to the capacitors will be about 14.1 volts. If there is no current draw from the capacitors (that is, with the load switched off), then each capacitor will charge to this 14.1 volts and the overall output voltage will be 28.2 volts and not the 20 volts which you might expect. You need to understand that as this is only a half-wave supply, there will be considerable ripple on the output voltage if the current draw is high.

Using one additional smoothing capacitor and paying attention to the voltage ratings of the capacitors, the 28 volts supply circuit might be like this:

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Rectification and Power Supplies

Rectification and Power Supplies
We now have the question of how do we turn an alternating voltage into a constant ‘direct’ voltage.   The crystal radio set operates by chopping off half of the alternating radio signal.   If we were to do this to the output from a mains transformer with an output of say, 12 Volts AC, the result is not very satisfactory:

Here, we have the situation shown in the upper diagram.   The output consists of isolated pulses at 50 per second.   You will notice that there is no output power for half of the time.   The negative part of the waveform is blocked by the high resistance of the diode while the positive part of the waveform is allowed through by the low resistance of the ‘forward-biased’ diode.   It should be remembered that the diode drops 0.7 Volts when conducting so the output of the half-wave rectified transformer will be 0.7 Volts lower than the transformer’s actual output voltage.

If four diodes are used instead of one, they can be arranged as shown in the lower diagram.   This arrangement of diodes is called a ‘bridge’.   Here the positive part of the waveform flows through the upper blue diode, the load ‘L’ and on through the lower blue diode.   The negative part flows through the left hand red diode, the load and then the right hand red diode.   This gives a much better output waveform with twice the power available.   The output voltage will be 1.4 Volts less than the transformer output voltage as there are two silicon diodes in the supply chain.

The output from even the full-wave rectifier is still unsatisfactory as there is a voltage drop to zero volts 100 times per second.   Only a few devices operate well with a power supply like that, an incandescent bulb as used in a car can use this output, but then, it could use the original AC supply without any rectification.   We need to improve the output by using a reservoir device to supply current during those moments when the voltage drops to zero.   The device we need is a Capacitor which used to be called a ‘condenser’.   The circuit of a mains unit using a capacitor is shown here:

This produces a much better result as the capacitor stores some of the peak energy and gives it out when the voltage drops.   If the load on the unit is light with not very much current taken from it, the output voltage is quite good.   However, if the current drain is increased, the output voltage gets dragged down 100 times per second.   This voltage variation is called ‘ripple’ and if the unit is supplying an audio system or a radio, the ripple may well be heard as an annoying hum.   The larger the capacitor for any given current draw, the smaller the ripple.

To improve the situation, it is normal to insert an electronic control circuit to oppose the ripple:

This circuit uses one new component, a new variety of diode called a ‘Zener’ diode.   This device has an almost constant voltage drop across it when its current-blocking direction breaks down.   The diode is designed to operate in this state to provide a reference voltage.   The circuit merely uses a tiny current from the top of the zener diode to drive the Darlington pair emitter-follower transistors used to provide the output current.

With this circuit, when the output current is increased, the resistance of the transistor pair automatically reduces to provide more current without varying the output voltage.   The 1K resistor is included to give the transistors a completed circuit if no external equipment is connected across the output terminals.   The zener diode is chosen to give 1.4 Volts more than the required output voltage as the two transistors drop 1.4 Volts when conducting.

You should note that the output transistor is dropping 6 Volts at the full supply current.   Watts = Volts x Amps so the power dissipated by the transistor may be quite high.   It may well be necessary to mount the transistor on an aluminium plate called a ‘heat sink’ to keep it from overheating.   Some power transistors, such as the 2N3055, do not have the case isolated from the active parts of the transistor.   It is good practice to use a mica gasket between the transistor and the heat-sink as it conducts then heat without making an electrical connection to the metal heat-sink.

A capacitor, being an electrical reservoir, can be used as part of a timer circuit.   If the current flow into it is restricted by passing it through a resistor.   The length of time between starting the flow on an empty capacitor, and the voltage across the capacitor reaching some chosen level, will be constant for a high-quality capacitor.

As the voltage increase tails off, it becomes more difficult to measure the difference accurately, so if the capacitor is to be used for generating a time interval, it is normal to use the early part of the graph area where the line is fairly straight and rising fast.

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What is a Coil

If you take a cardboard tube, any size, any length, and wind a length of wire around it, you create a very interesting device.   It goes by the name of a ‘coil’ or an ‘inductor’ or a ‘solenoid’.

This is a very interesting device with many uses.   It forms the heart of a radio receiver, it used to be the main component of telephone exchanges, and most electric motors use several of them. The reason for this is if a current is passed through the wire, the coil acts in exactly the same way as a bar magnet:

The main difference being that when the current is interrupted, the coil stops acting like a magnet, and that can be very useful indeed.   If an iron rod is placed inside the coil and the current switched on, the rod gets pushed to one side.   Many doorbells use this mechanism to produce a two-note chime.   A ‘relay’ uses this method to close an electrical switch and many circuits use this to switch heavy loads (a thyristor can also be used for this and it has no moving parts).

A coil of wire has one of the most peculiar features of almost any electronic component.   When the current through it is altered in any way, the coil opposes the change.   Remember the circuit for a light-operated switch using a relay?:

You will notice that the relay (which is mainly a coil of wire), has a diode across it.   Neither the relay nor the diode were mentioned in any great detail at that time as they were not that relevant to the circuit being described.   The diode is connected so that no current flows through it from the battery positive to the ‘ground’ line (the battery negative).   On the surface, it looks as if it has no use in this circuit.   In fact, it is a very important component which protects transistor TR3 from damage.

The relay coil carries current when transistor TR3 is on.   The emitter of transistor TR3 is up at about +10 Volts.   When TR3 switches off, it does so rapidly, pushing the relay connection from +10 Volts to 0 Volts.   The relay coil reacts in a most peculiar way when this happens, and instead of the current through the relay coil just stopping, the voltage on the end of the coil connected to the emitter of TR3 keeps moving downwards.   If there is no diode across the relay, the emitter voltage is forced to briefly overshoot the negative line of the circuit and gets dragged down many volts below the battery negative line.   The collector of TR3 is wired to +12 Volts, so if the emitter gets dragged down to, say, -30 Volts, TR3 gets 42 Volts placed across it.   If the transistor can only handle, say, 30 Volts, then it will be damaged by the 42 Volt peak.

The way in which coils operate seems weird.   But, knowing what is going to happen at the moment of switch-off, we deal with it by putting a diode across the coil of the relay.   At switch-on, and when the relay is powered, the diode has no effect, displaying a very high resistance to current flow.   At switch-off, when the relay voltage starts to plummet below the battery line, the diode effectively gets turned over into its conducting mode.   When the voltage reaches 0.7 Volts below the battery negative line, the diode starts conducting and pins the voltage to that level until the voltage spike generated by the relay coil has dissipated.   The more the coil tries to drag the voltage down, the harder the diode conducts, stifling the downward plunge.   This restricts the voltage across transistor TR3 to 0.7 Volts more than the battery voltage and so protects it.

Solenoid coils can be very useful.   Here is a design for a powerful electric motor patented by the American, Ben Teal, in June 1978 (US patent number 4,093,880).   This is a very simple design which you can build for yourself if you want.   Ben’s original motor was built from wood and almost any convenient material can be used.   This is the top view:

And this is the side view:

Ben has used eight solenoids to imitate the way that a car engine works.   There is a crankshaft and connecting rods, as in any car engine.   The connecting rods are connected to a slip-ring on the crankshaft and the solenoids are given a pulse of current at the appropriate moment to pull the crankshaft round.   The crankshaft receives four pulls on every revolution.   In the arrangement shown here, two solenoids pull at the same moment.

In the side view above, each layer has four solenoids and you can extend the crankshaft to have as many layers of four solenoids as you wish.   The engine power increases with every layer added.   Two layers should be quite adequate as it is a powerful motor with just two layers.

An interesting point is that as a solenoid pulse is terminated, its pull is briefly changed to a push due to the weird nature of coils.   If the timing of the pulses is just right on this motor, that brief push can be used to increase the power of the motor instead of opposing the motor rotation.   This feature is also used in the Adams motor described in the ‘Free-Energy’ section of this document.

The strength of the magnetic field produced by the solenoid is affected by the number of turns in the coil, the current flowing through the coil and the nature of what is inside the coil ‘former’ (the tube on which the coil is wound).   In passing, there are several fancy ways of winding coils which can also have an effect, but here we will only talk about coils where the turns are wound side by side at right angles to the former.

    1. Every turn wound on the coil, increases the magnetic field.   The thicker the wire used, the greater the current which will flow in the coil for any voltage placed across the coil.   Unfortunately, the thicker the wire, the more space each turn takes up, so the choice of wire is somewhat of a compromise.
    1. The power supplied to the coil depends on the voltage placed across it.   Watts = Volts x Amps so the greater the Volts, the greater the power supplied.   But we also know from Ohm’s Law that Ohms = Volts / Amps which can also be written as Ohms x Amps = Volts.   The Ohms in this instance is fixed by the wire chosen and the number of turns, so if we double the Voltage then we double the current.For example: Suppose the coil resistance is 1 ohm, the Voltage 1 Volt and the Current 1 Amp.   Then the power in Watts is Volts x Amps or 1 x 1 which is 1 Watt.

      Now, double the voltage to 2 Volts.   The coil resistance is still 1 ohm so the Current is now 2 Amps.   The power in Watts is Volts x Amps or 2 x 2 which is 4 Watts.   Doubling the voltage has quadrupled the power.

      If the voltage is increased to 3 Volts.   The coil resistance is still 1 ohm so the Current is now 3 Amps.   The power in Watts is Volts x Amps or 3 x 3 which is 9 Watts.   The power is Ohms x Amps squared, or Watts = Ohms x Amps x Amps.   From this we see that the voltage applied to any coil or solenoid is critical to the power developed by the coil.

  1. What the coil is wound on is also of considerable importance.   If the coil is wound on a rod of soft iron covered with a layer of paper, then the magnetic effect is increased dramatically.   If the rod ends are tapered like a flat screwdriver or filed down to a sharp point, then the magnetic lines of force cluster together when they leave the iron and the magnetic effect is increased further.

If the soft iron core is solid, some energy is lost by currents flowing round in the iron.   These currents can be minimised by using thin slivers of metal (called ‘laminations’) which are insulated from each other.   You see this most often in the construction of transformers, where you have two coils wound on a single core.   As it is convenient for mass production, transformers are usually wound as two separate coils which are then placed on a figure-of-eight laminated core.

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