How to Emit Short Electric Impulse?

Discussion in 'General Electronics Chat' started by MrSignal, Jan 26, 2012.

  1. MrSignal

    Thread Starter New Member

    Jan 26, 2012
    I need an electric stimulator that emits short impulses of electric potential for an experiment.

    I would just use several batteries with two wires, but I need the impulse to be very short, in the order of a millisecond or less. I need to be able to adjust both the potential (<100 volt) and duration (~1 ms).

    My questions:

    1) Is there any stimulator like this available to buy?

    2) If not, are there components I can buy and connect to a few batteries to cut of the voltage after for example one millisecond, to create a short impulse?

    I guess I could use some kind of TENS therapy machine, but as I understand it they don’t emit a single impulse but rather a series of impulses.

    3) Can I manually set a TENS device to send only one impulse?

    I do have an oscilloscope with a signal generator which I could use, except that it only emits 2 Volts and minimum duration seems to be 4 milliseconds which is too long. I could use an amplifier (or two) but it would not solve the duration.

    All advice is very welcome!

    Thanks in advance!
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    Ho wmuch current do you need, i.e what do you want to stimulate, in other words what is the load?

    Does the pulse width have to be adjusted independently from the voltage level?
  3. MrSignal

    Thread Starter New Member

    Jan 26, 2012
    I need something like 20-70 mA.

    I am not sure of the resistance, but I guess something like 1000 ohm.

    I do not know current (exactly) nor resistance, therefore the need to adjust the voltage and checking results of the experiment. I do know that the range of current is the range mentioned above.

    The adjustability of the duration is not that important, I guess, as long as I can keep it very short (< 1ms).
  4. Papabravo


    Feb 24, 2006
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    Dry skin is in the 200k range, condective wet maybe rown to 10k. Stay far away from 50mA, it it lethal. Forrest M. Mims III published a " Neon Lamp Power Source" using a 555 with a RS 273-1380 step up transformer. Connect 555 as one-shot, use trans former as output or keep rectifier in and switch with another 555 & FET.
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009

    When I read the specs, the word "Taser" popped into my mind.
  7. Georacer


    Nov 25, 2009

    It would be safer if you told us what your load is. Pure resistive loads have different responses than purely inductive/capacitive loads and you don't sound too sure about that 1000Ω. Could it be around the area of tenths of thousands of Ohms?
  8. PaulEE


    Dec 23, 2011
    Besides all that, if you, in your troubleshooting (if there is any) charge up an inductive load unknowingly, it could back-emf your entire circuit (and maybe you) up in smoke...or at least, give you a nice shock and fry some drive transistors.

    Very tall (high voltage), short pulses can be tricky. All of a sudden, the switching speed of devices, along with parasitic capacitance and inductance, can cause nominally sharp square waves to be more and more rounded from the RC RL or RLC effects.

    Ideally, you'll just ask about your experiment circuit directly. We can save you lots of grief :)