Voltage following [tour 30]

All controllers made by 4QD work with a voltage input, normally derived from a potentiometer. However it’s the voltage input that determines the speed. The controller cannot tell whether that voltage is coming from a pot or a ‘black box’, so you can feed them from a microcontroller or other voltage source, we call this voltage following.

On most controllers*, this voltage is adjustable by the gain preset. Typically you need a minimum of 0-3v but you can use 0-10v or 0-B+,  Simply adjust the controller’s internal gain preset to suit [*note; the Porter range do not have a gain control].

In the case of a feed from a microcontroller, you’ll normally be using a PWM output and adjusting the PWM duty cycle. The controller will react to the PWM’s average voltage as if it was a straight d.c. voltage.

If the frequency of the PWM signal is too low, then you will get a modulated signal through to the motor. This can be solved by fitting a smoothing RC circuit.

Since all controllers include pot fault detection, you will need to connect a resistor in place of the pot, to stop this feature engaging.

With the Uni controller, the pot fault detection needs to be deactivated, this is described in the manual.

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