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[on:]

Here is my physiology project 

I'm building a muscle stimulator that will have to control 4 groups of frog leg muscles so that i can achieve movement across 2 articulations.
The source for the impulses will be the standard lab stimulator but it has only 1 pair of electrodes and for this experiment i need 4 pairs.
I want the arduino to turn on and off the electrodes at certain times and for certain periods of time. can somebody give me a rough schematic on how to build the circuit, or at least what should i use for switches (transistors, relays ?), what arduino pins to use and how to turn that 1 pair of electrodes into 4 ?
I'm relatively new to electronics and the arduino, but would very much like to make this project happen.

Thank you, sorry for my english...

[Reply #1 on:]

Well - first we'd have to know the output voltage of the lab stimulator, as well as its current capability; I suspect the former would be somewhat high, while the latter to be fairly low.

It might turn out to be easier to build 4 homemade TENS units, and control them with the Arduino; circuits I have seen on the internet for a homemade TENS seem to all use a 555 timer in some fashion; the Arduino could probably substitute for that using PWM. More or less you would be feeding a PWM signal into a voltage multiplier circuit, whose output would go to the electrodes.

[Reply #2 on:]

I haven't yet collected the parameters of the lab stimulator (will do that tomorrow), but here is a picture of an application we use to simulate working with it. should be enough to understand what it's capable of.

http://www.clabs.de/SimMuscle-Labpic.htm

[Reply #3 on:]

Hmm - only up to .5 volts, correct? Well - then maybe not much current at all; I'm not really certain what could be used to switch such low voltages and currents (maybe small signal transistors or such).

[Reply #4 on:]

Could you not just use 4 "stimulators" like the top left module in the picture?