Luminescent Generator

When spun rapidly between the fingers, a bipolar stepper motor will generate around 10VAC. If this is stepped up with a small 240V to 6-0-6V transformer in reverse (with series connected secondaries), a small bipolar stepper motor is capable of powering a standard 5cm by 6cm luminescent sheet at full brightness. These are designed to be powered from 20V to 200VAC (typically 115VAC), producing 1.5 candelas of light - which will dimly light the average room, or adequately light a camp table. They are manufactured by Seikosha (RS Components Cat. 267-8726).

Circuit diagram:

Luminescent Generator Circuit Diagram

The transformer should be a small one (around 100mA or so), otherwise efficiency is compromised. The wires of the motors two phases are usually paired white & yellow and red & blue. Just one of these phases is employed in the circuit. If a small bipolar stepper motor from a discarded 3.5-inch disk drive is used, the Luminescent Generator may be built into a very small enclosure. To sustain rapid, smooth spinning of the motor, a geared handle may be added.

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IC 2N3906 Simple signal generator circuit

This circuit is a simple signal.It can generate signals, both light and sound Alternating.Which can be applied to work. For example Taillight of bicycle or Turn left and the right of the bicycle. Etc.
When entering into power supply circuit.

by circuit will have Q1 and Q2 to be astable multi vibrator. This will work in any way ON and OFF.Or vice versa on all the time.And Pin Collection (C) of the two transistors.Connected to the light source device (LED1-LED4).For the audio source device is Buzzer BZ1.While the one ON transistor will allow the device is connected to pin C is running.The signal alternates between light and sound all the time.

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Simple Function Generator Circuit Using IC 555

This circuit of a simple function generator circuit explained here generates sawtooth and triangle waveforms at a frequency set by an external control voltage. Current source Ol draws a current l from timing capacitor C.
Simultaneously current source O2 draws the same current from current mirror O3, O4; this is set up (by R1 and R2) to deliver (from the collector of O4) twice the current leaving O2. Hence C receives a current 2 l from the top rail, at the same time delivering l to the bottom rail, the net effect being that the capacitor is charged by a constant current l, its voltage rising linearly until the 555s upper trigger point (at 2/3Vcc) is reached. - The output (pin 3) then goes low, as does the open~collector discharge output at pin 7.

 The latter shunts the output of the current mirror to earth, D1 becoming reverse-biased and isolating C. Now only current source O1 is connected to the timing capacitor which is now linearly discharged by current I. ln this way C is alternately charged and discharged. When the voltage on C falls to the 555s lower trigger point at 1/3Vcc, the output and discharge pins go high, and the  cycle recommences; the repetition frequency is determined by the magnitude of I, which is set by the voltage applied at the input point A. With the component values shown, the frequency range is from approx.  2.5 kHz to less than 10 Hz, as the control voltage varies from +10 V to zero; the frequency is directly proportional to the control voltage. Other ranges may be obtained by altering the value of C.

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Mini High Voltage Generator Circuit

Here’s a project that could be useful this summer on the beach, to stop anyone touching your things left on your beach towel while you’ve gone swimming; you might equally well use it at the office or workshop when you go back to work. In a very small space, and powered by simple primary cells or rechargeable batteries, the proposed circuit generates a low-energy, high voltage of the order of around 200 to 400 V, harmless to humans, of course, but still able to give a quite nasty ‘poke’ to anyone who touches it.

Quite apart from this practical aspect, this project will also prove instructional for younger hobbyists, enabling them to discover a circuit that all the ‘oldies’ who’ve worked in radio, and having enjoyed valve technology in particular, are bound to be familiar with. As the circuit diagram shows, the project is extremely simple, as it contains only a single active element, and then it’s only a fairly ordinary transistor. As shown here, it operates as a low-frequency oscillator, making it possible to convert the battery’s DC voltage into an AC voltage that can be stepped up via the transformer.

Using a centre-tapped transformer as here makes it possible to build a ‘Hartley’ oscillator around transistor T1, which as we have indicated above was used a great deal in radio in that distant era when valves reigned supreme and these was no sign of silicon taking over and turning most electronics into ‘solid state’. The ‘Hartley’ is one of a number of L-C oscillator designs that made it to eternal fame and was named after its invertor, Ralph V.L Hartley (1888-1970). For such an oscillator to work and produce a proper sinewave output, the position of the intermediate tap on the winding used had to be carefully chosen to ensure the proper step-down (voltage reduction) ratio.

Here the step-down is obtained inductively. Here, optimum inductive tapping is not possible since we are using a standard, off-the-shelf transformer. However we’re in luck — as its position in the centre of the winding creates too much feedback, it ensures that the oscillator will always start reliably. However, the excess feedback means that it doesn’t generate sinewaves; indeed, far from it. But that’s not important for this sort of application, and the transformer copes very well with it.

The output voltage may be used directly, via the two current-limiting resistors R2 an R3, which must not under any circum-stances be omitted or modified, as they are what make the circuit safe. You will then get around 200 V peak-to-peak, which is already quite unpleasant to touch. But you can also use a voltage doubler, shown at the bottom right of the figure, which will then produce around 300 V, even more unpleasant to touch. Here too of course, the resistors, now know as R4 and R5, must always be present. The circuit only consumes around a few tens of mA, regardless of whether it is ‘warding off’ someone or not! If you have to use it for long periods, we would however recommend powering it from AAA size Ni-MH batteries in groups of ten in a suitable holder, in order not to ruin you buying dry batteries.

Circuit diagram:

Warning!
If you build the version without the voltage doubler and measure the output voltage with your multimeter, you’ll see a lower value than stated. This is due to the fact that the waveform is a long way from being a sinewave, and multimeters have trouble interpreting its RMS (root-mean-square) value. However, if you have access to an oscilloscope capable of handling a few hundred volts on its input, you’ll be able to see the true values as stated. If you’re still not convinced, all you need do is touch the output terminals...

To use this project to protect the handle of your beach bag or your attachecase, for example, all you need do is fix to this two small metallic areas, quite close together, each connected to one output terminal of the circuit. Arrange them in such a way that unwanted hands are bound to touch both of them together; the result is guaranteed! Just take care to avoid getting caught in your own trap when you take your bag to turn the circuit off!

Copyright : Elektor Electronics 2008

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