I take it you mean one of these John?

The speed control is on the centre pin of the pot marked 100k with the control knob. There are three connectors soldered to the board. One side will be ground, the other at supply (+5 or 12V), and the centre pin connects to a wiper varying between 0 and supply as the know turns.

This version of the PSU would be easier to work with because the pot is detached and can be 'got at'. The wiper is on the White wire.

In principle, fast can be achieved by wiring a switch between supply and the wiper. Unfortunately not as easy as that. For example, if the wiper is turned to 0V, connecting supply to it will cause magic smoke. When the button is pressed, it needs to disconnect the pot before applying volts. The other complication is the need for a reverse switch : the controller is unidirectional, so it's output has to be switched too.

Getting complicated: the control circuit has to flip the motor direction, then disconnect the pot, then apply the go fast voltage. And because it's bad for the electronics to from zero to hero in microseconds, it would pay to accelerate gently up to speed by charging a capacitor through a resistor.

Certainly can be done, but not by soldering a few wires. I'd be inclined to keep it simple with a reversing switch and manually turning the knob.

Dave

I very roughly followed this video:

**LINK**

Full speed can be achieved by completely bypassing the controller, but (depending on the power supply) may over-drive the motor. I am applying 19 volts to my 12V wiper motor at full speed. I thought that was enough! I might yet change it for a 24V wiper motor, but all the bits I needed (apart from the speed controller) were easily to hand.

The video offers the alternative wiring dodge for the speed controller I purchased for about £12.

I chose to use a wiper motor, after looking at the physical sizes of the two options (wiper or winder motor).

edited to say sorry for the adverts before the video starts.🙂

Edited By not done it yet on 19/07/2021 13:40:15

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That’s very tidy, Mike … thanks for the link

MichaelG.

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Given the demise of Maplin : May I ask if this is the relevant module ?

https://www.rapidonline.com/mfa-919d2-series-pwm-voltage-speed-regulator-modules-82349

Edited By Michael Gilligan on 19/07/2021 17:27:56

Hi John, Guys,

When I built my window screen wiper motor driven mill table drive, I used a variable voltage lab type power supply. Mine supplies 30 volts at 3 amps. I just use the whole 30 volts for fast traverse and around 7 volts for actual milling.

My direction control is via a tumbler gear very similar to the one found on a Myford lathe, giving me forward/stop/ and reverse directions.

This is a picture of mine mounted on the left hand side of the table. I just pull the white knob out and lift or lower the lever to select the direction or neutral. It also has the advantage that I can still use the handwheel at the other end when neutral is selected.

All the gears were salvaged from printers. photocopiers and the like. The motor unit is a "Trico" one salvaged from the local scrapyard.

Thanks for that, Mike

MichaelG.