Variable Speed Controller for 12v DC

You need a variable resistor, a.k.a. rheostat.

GO TOO RADIO SHACK AND BUY THERE BOOK !! IT VERY CHEEP !!G

A rheostat will certainly reduce the voltage, but the torque will drop very quickly and the motor will stall.

Very simple !

Take one out of a battery powered drilling machine.

12 or 13.2 volts.

easy to find also as :screps

GDP

Re: Variable Speed Controller for 12v DC I need a circuit for a speed controller for a 12v DC motor. Current is max 10 amps.

Electric drills and LED units that must vary speed while keeping constant amplitude use a square wave chopping circuit. I purchased one for $80.00 from CED about two months ago for a lighting circuit with low power. You could dissassemble an electric drill and use the controller to see if it works. (Get it back together again before the owner sees it). Unit is about 1" x 3" board.

Use this link. http://www.educypedia.be/electronics/circuitsmotorcontrol.htm

KB Electronics has a SCR-style motor controller board good for up to 40 amps.

The model is KBBC-24M, click http://www.kbelectronics.com/data_sheets/d905.pdf for a data sheet.

Regards, Delmar Schmidt
Melfi Technologies Houston
www.melfitechnologies.com

I KB Electronics website down for some reason, as the link provided does not work.

BR Raj

Thank you for the spec sheets on power control. I am sure that those would not fit in an electric drill, and my needs are for LED lighting anyway. Do you have a source for smaller items that I can use for probably not more than 1Amp at 12VDC?

One of the best things I have used for control DC motors is PWM signal into a H bridge.

So to give you an idea about PWM circuit go to http://www.cpemma.co.uk/pwm.html

Saludos!

Thank you. Exactly what i was looking for with some good links too. Perhaps you can identify an LED fixture that I have from Japan? It is obviously designed to be plugged into a standard wedge base, but I have not been able to decide which one. Partly because all the drawings in catalogs are very small. The light is 10 mm in diameter, says 12V on it and is about 25 mm long. there are three separate squashed LED lenses fixed inside the top of the housing. I made a drawing and could take a photo, almost anything except having to solder 200 of these into a fixture. I miss having access to the inventory at GE when I was working at the Stanford R&D place many years ago. Now I have a lot of hardware for wood products and manufacturing fixtures.

"Victors" by IFI RObotics

What is the application.... control the motor spped or it's for motion....?

Unusual application. I have a street rod with an electric fuel pump intended for racing, so it pumps much more fuel than I need and draws about 10 amps. I want to slow it down , to save power and reduce the noise.