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Pulsing circuit

Hi everybody. I have an idea for some wierd stuff (I don't want to say what it is untill it works), but I don't know how to make it and I don't know how to google it.

I need a circuit that uses one DC power source, and a capacitator, and it can't have any switches, it has to work all the time the power is conected. It needs to charge the capacitator and when it's full send all the electricity it to the "Parts"/electronics. But "Parts"/electronics shouldnt get any power while capacitator is charging.

The point is to get regular pulses with higher voltage than the power source can provide.

Any help would be apreciated.

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google "joule thief"

Yup, the internet has everything!

This is a circuit I remember building from back-in-the-day. It is a simple cap/resistor/transistor set up to toggle 2 leds. This might not be exactly what you need but this should set you in the right direction --the circuit you need will be very similar to this one.


I don't have it. I think I understand the cricuit, and if I do I can use it for my needs. Can I just use half of the circuit, remove the diode (or make it a normal diode instead of LED), put a bigger capacitator and plug the muscle to the wires that should go to the transistor?

If I totaly misunderstood this circuit, how can I change the joule thief so it has 50000 times smaller frequency?

I've used this circuit, and it is pretty simple and works well. You cannot eliminate one side, but replacing one LED with a regular diode should work. Adjusting both 100k resistors will change the flash rate, with both sides having equal times. If you change the two 100k resistors so that they are two different values, than one side of the circuit will have more "on time" than the other (duty cycle). You could also replace the 100k resistors with potentiometers, so you can vary the flash rates and duty cycles on the fly. You can also change the capacter values. Higher values will have longer charge/discarge times.

The parts are usually pretty easy to get and are inexpensive. I suggest you build the circuit as-is so you gain some understanding. Then you can see about adapting this to your needs.

It sounds like you want a much higher voltage to be delivered to the muscles. What sort of current are you trying to deliver? You are not going to get too much current to flow through those transistors and LEDs only pass 20-40 mA. I think you would be replacing the LEDs and 470 ohm resistors with the connection to the muscles. You can get higher current transistors and diodes, plus your capacitor would need to rated for the voltages you are talking about.

Finally, may I just say that if I understand what you are doing, it sounds sort of dangerous and crazy? Please be careful about how much current you are working with. Try not to kill yourself of someone else, OK? Have you ever tried placing your tongue (briefly) to the terminals of a 9V battery? It stings but it won't kill or injure you. However, if you used a 12V car battery, which is capable of putting our MUCH higher current, you could really hurt yourself. You may need to have some sort of conductive paste or at least water on the muscle to make this work.

So I can make one bigger capacitator and replace it's led so it provides the shock, and make other side with bigger resistance and a normal diode so it takes longer between the shocks? Would that circuit send out one shock every second or two, or would it send power part of the time and not send it other part of the time? 

I will try to build it this weekend if I find good parts in my "pile of scavanged parts", and if not this project will have to wait becouse it takes too long to get to the store just for few parts...

I don't know how much current or voltage I need, but I have alot of diferent capacitators, and I would try it on the breadboard with bigger ones untill i have just enough power to get a muscle to contract. Well it is crazy, but if I go gradualy I will not kill, or even hurt myself (or my friend if I convince him to be my test subject). I tried the 9v battery ends, it isnt nice, but I also got shocked with some transformator or something from the same 9v battery and it didnt realy hurt, only made me contract all the muscles (teacher in elementary school shocked the whole class like that few times), and that's what i'm trying to achieve, but weaker and around every second

Well, you can get a pulse a lot of different ways. A 555 timer will do it or any kind of microprocessor will do it. You can also make a "dumb" circuit with just "regular" components to get a pulse as well. From there, if you need a higher voltage, you can click any flavor or transistor you want or click a relay. It is true that the charge/discharge rate of caps is often used to set the timing of things but I think you might be going at this the wrong way.

What is the eventual goal here?

Thank you for your fast reply.

The ultimate goal is to stimulate a muscle.

I would need only regular pulses of around 50V (I don't know how much Volts I actualy need for this, I would make some tests first, i  have volonteurs to be shocked) from a small battery (1.2/1.5V, AAA or AA), to do that. I don't think I can get 555 timer or something like that here in croatia, and if i order it online it would cost too much, I would like this to be as cheap as possible.