Clarkey,Clarkey wrote:Thanks, GV for pointing that post out to me.
After a little while looking through what you had produced I came across the Instructables article on controlling motors with an Arduino. The circuit diagram depicts what I've created almost exactly, the only difference being that they use a TIP120 and my circuit uses a TIP122 (to my knowledge there isn't much of a difference between them), so I'll instead refer people to: http://www.instructables.com/files/deri ... .LARGE.jpg which comes from: http://www.instructables.com/id/Use-Ard ... trol-moto/
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At the moment I'm interested in creating a circuit that can have several 9v batteries connected to it (utilising one at a time), that can automatically change between them as the voltage in the battery being used reaches a critical point (I suppose at around ~4-5v the battery begins to loose it's efficacy in producing a stimulating vibration). This would allow me to torment my subjects for extended periods of time (mwahahahaha!). I could attempt to imagine such a circuit, however my knowledge of electronics is still limited and I'm not sure what I would be looking for online, so it would be appreciated if someone could point me in the correct direction(? (please!))
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Clarkey
The TIP120 or TIP122 are both fine devices for controlling higher power DC devices from an Arduino. The circuit from instructables.com is OK, but not optimal. Both the TIP120 and TIP122 have built-in diodes to protect the transistor(s) from the inductive back-kick that happens when switching off inductive loads (like a motor), so you can omit those if you like. I would lower the base resistor from 1K to 470 ohms, to ensure that the transistor is completely saturated when driven on; it'll run cooler that way, and the current from the Arduino pin will still be well below its per-pin current limit (under 10 mA vs. a limit of 40 mA.)
9 volt batteries are an expensive way to buy battery power. I think you'll do better with six AA or C cells in series, either one-shot or rechargeable ones. Even better, use a (boost or SEPIC) switching regulator, and you'll be able to use much more of the energy from the batteries for your kinky pleasure, because the switching regulator can make use of the batteries' power even when they're discharged almost to zero. I've used little switching regulators from http://www.pololu.com/catalog/category/84 and had good luck with them. There are probably other sources for such modules; I have no affiliation with pololu except as a satisfied customer.
Hope this helps!