I have a DC motor speed controller (PWM) that uses a 100 kΩ potentiometer to adjust motor speed. I also have an electronic throttle pedal that used a 49E Hall-Effect sensor (+5 V, 0.8-4.2 V signal, 1 K KΩ). I want to use this pedal with this speed controller.
I measured the voltage drop across the potentiometer and it is 5 V. I confirmed that the pedal's signal changes from 0.8 V (released) to 4.2 V (fully pressed) when given 5 V.
What would be a right way to replace the potentiometer in the speed control unit with a Hall-effect sensor? Note that I would prefer to preserve full speed control range (from 0% to 100%).
If you're curious about my application: replacing binary on/off throttle in kids ride on car.
PWM controller built-in potentiometer works like this:
- Max speed: GND to wiper = 0 V, wiper to V+ = 5 V
- Min speed: GND to wiper = 5 V, wiper to V+ = 0 V
And Hall-effect pedal is opposite:
- Max speed (fully pressed): GND to signal = 4.2 V
- Min speed: GND to signal = 0.8 V
So as a drop-in replacement pedal it will behave more like a break pedal :)
On further examination, it appears that the potentiometer's GND (I mean, one of its legs that I referred above as GND) is connected directly to input GND of the PWM controller (where the negative terminal from battery goes). So, from a practical standpoint, it's probably safe to assume that I also have GND - Xv at my disposal (Xv however is variable, since it's coming from an unregulated battery).
But I think this extra voltage source makes this question less general and less useful for other people.