Electrial Stimulator

Can you give me a little more data of the output signal, waveform, amplitude, duty cycle. Then I will try to give you a diagram.

Anders

RESPECTED SIR,

THANKS FOR YOUR reply .The output signal is square wave with amplitude of 300microampheres.the duty cycle is 0.5 or 50%

Voltage voltage voltage,

What is the amplitude and shape of voltage that you would like to stimulate?

the circuit that i wanted to fabricate is to provide energy supplementation to the wounds . so the device was supposed to be as compact as possibe.so i am waiting for your circuit diagram

You refer to energy supplementation to the wounds. This leads me to believe that this operation is to be performed on a patient with some form of trauma... such as a cut (to make things simple).

To do a constant current source, we need to have an idea of load resistance. Just for the heck of it, I took my trusty ohm meter and measured the skin resistance across one inch of bare skin on my arm, and came up with approximately 10 Megohm.

To get 300 microamp through 10 megohms of resistance would require (using E = I x R), 3000 volts... Thus the constant current source would have to be powered from at least 3Kv. Anyone know of transistors that operate at this voltage??

Now I AM making several guesses here, and could be totally out to lunch without more info.

Sincerely

Bill

And for speculation, let's assume that they need it to operate from a 9 volt alkaline battery. That leads to some more fun design work. 9 v dc ----> 3Kv dc.

Explain to me how one of the replies refers to current in terms of amplitude. Am I ignorant?

A simple constant current generator driven by a 555 timer chip will do the job nicely.

John.

Run the 555 at 2 Hz with a flip flop following. The 555 cannot generate a 50% duty cycle.

Bill

Hi Sciesis,

You can do the 50/50 duty cycle quite simply. The 555's of yesteryear we were told cannot; but alas even that was not quite so. With the bipolar technology 555s, you could use a diode and resistor extra to make it happen, but these days with CMOS 555, you can drive the RC timing network directly from the output to get 50% duty cycle; as long as the output voltage saturation is symetrical on the +ve and -ve then you're OK.

Hmmm... Now you have me curious. Is there anyway you could get me a schematic or direct me to a manufacturers app note? Typically in the past, I have used 555s for simple clock generation, using a single supply, to drive a bunch of logic. I must admit though that a diode and additional resistor are usually cheaper than a flip flop. I just remember that the design equations blew up as a 50% duty cycle was approached. I have never run one from dual supplies.

E-mail here is Sciesis2@aol.com

Much Thanks

Bill