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

Bazz4CQJ · 5th Dec 2017, 4:00 pm

Hi Hugo, yes I'd certainly be interested if you can find that circuit. When I searched Google, I found numerous circuits based on pulse-width control, but only 2 where there was a feedback element. I don't have the expertise to design anything.

Continuing to assess what I have got with this one, it's working well on the SLA battery. I reduced the speed of the drill to about the lowest speed at which I thought it would do useful work and then measured the voltage being supplied as I loaded it. With no load it was 6V and that rose to ~7.5V when loaded, so it definitely is helping to maintain torque. I'm sure that modelling it in SPICE would help match the circuit to my particular motor. But even in its present configuration, looks like it will be superior to my PW controller.

B

5th Dec 2017, 4:00 pm	#14
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	Re: Mini-drill; Speed Controller Problem Hi Hugo, yes I'd certainly be interested if you can find that circuit. When I searched Google, I found numerous circuits based on pulse-width control, but only 2 where there was a feedback element. I don't have the expertise to design anything. Continuing to assess what I have got with this one, it's working well on the SLA battery. I reduced the speed of the drill to about the lowest speed at which I thought it would do useful work and then measured the voltage being supplied as I loaded it. With no load it was 6V and that rose to ~7.5V when loaded, so it definitely is helping to maintain torque. I'm sure that modelling it in SPICE would help match the circuit to my particular motor. But even in its present configuration, looks like it will be superior to my PW controller. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. Last edited by Bazz4CQJ; 5th Dec 2017 at 4:10 pm.