Motor frame finished

Ken and Louis finished the frame for the motor today and checked everything lines up with the drive shaft correctly. So at 6pm I took it home and painted it with epoxy primer.

Then late when I couldn't sleep I got up and finished the throttle control. That now works correctly too.

My original design didn't have the extra drain resistor for the transistor relay driver or the resistor on the output of the throttle control. But with those added the system worked very well indeed.

Basically the cross wired dual gang potentiometer has one fading up while the other is fading down and visa versa. By adding them through a couple of diodes, from the central off position the voltage increases in each direction.

Using a ubiquitous 741 op-amp across the two potentiometers, when the voltage on one is greater than the other the op-amp triggers state. This goes through a 2N2222 driver transistor to a relay. I could drive the controller direct, with a couple of op-amps, but using the relay isolates my circuit from the controller totally.

Simple and effective.

Tomorrow if all goes well the battery frame will be finished.