UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Mini-drill; Speed Controller Problem

TrevorG3VLF · 27th Nov 2017, 9:09 pm

I currently use a 12V battery charger which is adequate to drive a DC motor running a coil winder.

I did an experiment with a rectified but not smoothed supply controlled by an SCR. An op-amp compared the motor voltage with an adjustable voltage. If the motor back EMF voltage was too low, the the SCR was triggered. Thus the speed was measured 100 times a second and corrected as necessary. I found that this was not necessary when winding thin wire so has been put in the round tuit pile. A battery charger and Variac is used at present.

27th Nov 2017, 9:09 pm	#8
TrevorG3VLF Rest in Peace Join Date: Apr 2011 Location: Matlock, Derbyshire, UK. Posts: 1,378	Re: Mini-drill; Speed Controller Problem I currently use a 12V battery charger which is adequate to drive a DC motor running a coil winder. I did an experiment with a rectified but not smoothed supply controlled by an SCR. An op-amp compared the motor voltage with an adjustable voltage. If the motor back EMF voltage was too low, the the SCR was triggered. Thus the speed was measured 100 times a second and corrected as necessary. I found that this was not necessary when winding thin wire so has been put in the round tuit pile. A battery charger and Variac is used at present.