I also just set up the analog voltage control and ON/OFF of the VFD from my Kflop/Kanalog controller and it all works nicely. I see no fluctuation in the speed as it is, on the bench, nice and sweet. The speed variation between what it says on the VFD panel and my own reading with a tachometer was practically bang on too.

For the on/off relay I've used a cheap SSR from RS, part number 720-3956. It only costs £6.62 and it operates at 24V. No diode needed.

Edward

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