I would like to replace the cable-connected remote control of a directional motor by a breadboard controlled by the arduino. Here is what the cable / remote control does:
And here is the inside of the remote:
The resistor at the back is on the +5V and is to the best of my knowledge a 3.9K. (color coding - and I also get this value when measuring, but in-circuit).
It seems to be a 20K sliding pot at the bottom and indeed when measure I get variations from 0 to 23K. This items controls speed on the remote control and is connecting the speed cable to ground.
When on the motor that this remote controls I plug a 0ohm resistor between +5V and and direction it works (but gets VERY hot after a very short while... I only discovered the 3.9K resistor later). Between +5V and speed the resistor starts smoking.
So: how do I reproduce this remote control on a breadboard to work with the arduino?
I am thinking: for the directional controls :
digital pin 1 --- transistor base
Emitter / Controller to +5V / left cable with a 3.9K resistor in the circuit
etc for the other 3 directions
... but what about the ground cable? What's that for? And how do I control speed (the 20K pot)? Is this a completely different and independant circuit? Is there a way to have a digital equivalent of the 20K pot effect?
oh - the remote has no battery. all its power comes from the motor.
Thanks for nay help!