Hi Alex and
![](https://i.imgur.com/evDSMvT.png)
to the forum,
The GM throttles use a Hall sensor instead of a potentiometer but the VEC500 controller allows either type to be selected.
The Honeywell SS49E Hall sensor is often used as a replacement for the original throttle Hall sensors, so feel free to look up the spec on these.
If you want to use a potentiometer, a 10,000 Ohm
(10k) should work fine, and the power dissipation should be less than 5mW
(0.005W).
The throttle signal is basically a variable voltage which is used to control the motor speed.
The throttle signal voltage is typically around 0.8~1V with the throttle released and the motor typically begins to run at ~1.25v and maximum motor speed is usually achieved with a signal voltage of around 3.25V.
The following graph is based on empirical data collected during several tests on a Magic Pie hubmotor:
![](https://i.imgur.com/vNRULlr.png)
I suspect that the active throttle signal voltage range will be very similar on the VEC-500 controller, but the rpm range is likely to be a lot higher.
![Roll Eyes ::)](https://goldenmotor.com/SMF/Smileys/default/rolleyes.gif)
I have just checked the voltages on a GM Hall sensor twist throttle with a measured 4.99V supply, and its output signal voltage ranged from 0.82V released to 3.60V at full throttle.
I don't have a VEC-500 controller to test, but I just measured the throttle signal current draw on a GM vector controller from a Magic Pie 4 hubmotor and the current went from 0.0mA released to 0.7mA
(0.0007A) at full throttle
(3.60V) so the input resistance is about 5,143 Ohms at full throttle according to my calculations.
![Wink ;)](https://goldenmotor.com/SMF/Smileys/default/wink.gif)
At 2.11V it was still only drawing 0.01mA of current, which equates to a resistance of 211 kOhms.
If your
DAC's voltage output can be kept within the typical working voltage range
(0.8-3.6V) and can also supply a maximum output current of ~1mA, then I think it should work.
Please note: The throttle signal voltage should also be within the 0.8~1V range when the controller is initially powered up, or the motor will not run due to a built in safety feature that prevents vehicles from taking off unexpectedly if the controller is powered up with the throttle accidentally applied.
Alan