I'm trying to use an arduino Uno to replace an older piece of equipment--a Grass SS88 square pulse generator. I don't need to reproduce the broad range of function, just a particular set. Specifically, I need to generate square wave pulses in a range of 1-10V, duration from 0.1-10 ms, and at a frequency up to 200 Hz.
I'm not experienced with electronics, but I've found a few ideas to start from. Particularly, using a relay to open/close a circuit at the desired voltage; however, I'm not sure of the relay's response time. I've also seen TRIACs mentioned, though I'm not clear how to use them.
In addition to controlling the open/closed state of the circuit, I'm looking for a way to reliably control the voltage on a 0.1-10ms time frame. I've seen diagrams that combine a capacitor and resistor to produce a low-pass filter that, combined with PWM duty time, can serve as a sort of analog control for voltage but the ramp up time is relatively long compared with the ideal pulse duration. Currently I'm set up with a 12V wall mart adapter plugged into a voltage regulator to bring the voltage down to 9V. If fine-tune control over the voltage from 1-10V is complicated, I could instead use a fixed voltage of 7V (the range of 1-10V is merely to extend the flexibility of the device to projects which haven't been thought of yet and not a necessity).
Thanks for your time. Let me know if there are any bits of information missing, I'm afraid I'm too new to the electronics side of this to know if I've left anything out.
If what you need is just digital pulses, it's pretty simple. If I recall correctly, most Grass devices give you a modest (tens of mA) "courtesy power supply (? +12V or so) that you can tap off from. Simple open-collector drives (ULN2803) is available in a through-hole package (perfect for protoboarding) and would probably do fine, up to tens of mA. But a TIP121, with an input resistor and (for safety) a diode to protect from reverse-voltage transients from any inductance lurking can really sink some serious current (Amps, if properly heat sunk. For analog (variable) voltages, an OpAmp is your friend, and can source or sink at least 5 mA without letting the magic smoke out; add a push-pull pair after the OpAmp if you need more current. If you don't need to control 120 VAC, you can get away without the hassle of Triacs.
Hope this helps!