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DDCSV VSO to pwm spindle control

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picclock:
Hi
Does anyone know where I can find details of how to change the analogue spindle output, VSO, to pwm. I am sure I have read about it but alas cannot find it. If I remember correctly it involves removing a capacitor from the board, but I cannot find the details.

I am working on an interface between the DDCSV and a brushless motor controller but it needs to be pwm.

On my brushless controller the control pot sits at ~140V dc above gnd. The motor stops below 0.6V, max speed at 5V. The speed is controlled by a 5K pot which has its top end supplied with a 5V regulator (7805), which I shall use to power the circuit.

Initial schematic below.

Best Regards

picclock

Apparently I don't need the transistor pull down shown in the schematic as the controller board already has a 1k pulldown.

picclock:
I have managed to find the original article I read on how to do this on facebook. It includes a schematic of the VSO output and the location of the capacitor to be removed.

https://www.facebook.com/groups/1724999967517167/permalink/2355817094435448/

Best Regards

picclock

picclock:
After some testing I concluded that although the PWM solution, removing C50, posted by yt liu works it comes with some caveats. Firstly the signal has a dc offset of about 2v (varies with pwm value), secondly, the amplitude is only 6V p-p. To correct this an additional capacitor must be removed, C38. This results in a 12v p-p output with no dc offset.

best regards

picclock

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