Controller Potentiometer

[Tt321b]

I had an old radio control remote lying around my house and wanted to see if I could hook it up to the robot controller. The potentiometers for the joysticks I measured to be 4k Ohms. I know that the robot controller gives 5V, it wants 0.00005 Amps through a 100k Ohm pot. So therefore the 4k Ohm pot would need 0.2 volts to get the 0.00005 Amps. So I got a 96k Ohm resistor(which would have 4.8 V across it) and put it in between pin 1 (positive) and one end of the pot. I put pin 4 (ground) on the other end of the pot and had pin 6 (y axis) on the wiper. The thing is that the motors don't turn when the pot is adjusted. Only when the joystick is all the way down the motors twitch. When I short over the resistor it spins but I have no control(I know that is supposed to happen with such a small pot). I have no idea what is wrong? Is the pot too weak and just creating a little noise?

[Al Skierkiewicz]

T,
The analog input to the RC is another resistor. So the 100K in the joystick forms a voltage divider with the internal resistor. ( This is part of the safeety feature of the OI so that it recognizes a joystick that has been pulled out of the connector) Since you are only moving +/- 2K there is not enough change to affect the PWM input to a Victor. Theoretically, if you were to calibrate the Victor to this pot it might be able to move a motor. I suspect that the range would be very limited though and would not suggest you use this pot.

[Tt321b]

Thank you for the reply.

Yea, I thought that the pot was too weak. But did I technically do it right becuase I think this is what you have to do to use a video game controller but those pots are bigger (10k i believe).

[Al Skierkiewicz]

Electrically the way to have done this was use two 47K resistors on either side of the pot. (The electrical equivalent when using all three terminals.) But still I think you have proved that it isn't going to work as intended.