Measure reversible voltage without PD drop?

[12407622]

Well, that worked out much easier than had been anticipated:

https://youtu.be/1_PeoERrCLw

12407622 

[ledtester]

Can you post a schematic of what you eventually went with?

Thanks - and congratulations on getting it working!

[12407622]

Can you post a schematic of what you eventually went with?

Thanks - and congratulations on getting it working!

Hi ledtester,

Boring old germanium diode bridge wired across the motor terminals, 10K pot from +output of that to gnd, with very tiny greencap (3mm x 8mm x 2mm) and 4V7 clamp zener from wiper output to gnd.

The running motor is disabled for 2ms, each 1/12th of a second, after which period the back EMF from 2 successive measurements is averaged.

Yet to be properly tuned PID does the rest. A small Kp, much larger Ki, and almost none, but some very small Kd.

Sorry, a diagram would be just scribble, as I'm still recovering from an 'accident' with the hard drive I kept all those type of programs on. I hope the description was clear enough for anyone to follow.

Thanks very much for your interest, and fabo suggestions, everyone. 

12407622

[12407622]

Hi,

A little larger smoothing capacitor added for better noise immunity, and a stop on collision facility added.

https://youtu.be/doWnCFVbF9Y

Circuit attached:

T.