I posted this in Motors because thats what it was at first, but it's turned into more Electrical and I haven't gotten a response there yet, so here we go.
I want to hook up a servo to the Edubot kit. It says how to do that in
page 7 of the eduManual (pwm outputs section). The only problem is the +battery pin shoots out 7.2 volts (or whatever the battery is currently at). The servo's we got in the kit are rated from 4.8v to 6v, so the controller's voltage needs to be dropped with a resistor. Thing is, I've never done these calculations, so I want to make sure they're right.
Ohm's law solved for resistance is R = E / I, or Resistance = Voltage / Amperage. I'm guessing E is the voltage supplied. As for amerage, the servo specs list two opperating currents: 7.7mA @ 6v for "Idle Current" and 180mA @ 6v for "Running Current". One gets a resistance of 935 ohms, and the other gets a resistance of 40 ohms. So the question is which do I use? I'm guessing I use the higher amerage (40 ohms), because thats the limit and the motor can take less current if it needs to, but like I said, I've never done this, so all of this is a complete guess.
So my question is to hook the servo's up to the 7.2 volt EduBot pwm ports, is the resistor I need to use 40ohm?
Computers have a nasty habit of doing exactly what you tell them to do instead of what you want them to do. - KenWittlief [more] 
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