View Full Version : PC power supply to run DC 12v motor...any links??

11-14-2004, 02:43 AM
I've got my 12v (power window)motors, computer power supply etc,,,now I need some links so I can read more about this. I've searched google and several CNC bbs...got a lot of good info but it's mostly about stepper/servo motors. I think I might go with a PWM but could use a variac if need be. I'm building a powerfeed for the quill on my mill. I found several old links for using these type of motors to control machines but they no longer come up...they are dead. Does anyone else have anymore info? Thanks.

Forrest Addy
11-14-2004, 03:22 AM
Here's what you need to control the motor RPM on your quill feed unit.


This is a 6 to 36 volt PWM DC motor control with pot speed adjustment for about $40.

Also search eBay under "PWM DC Motor" There's several that will do the job.

11-14-2004, 08:41 AM
Forrest...Thanks! I just sent the guy a message about shipping to Canada. Looks like a good deal to me.

11-14-2004, 08:47 PM
Ckt board looks a bit puny to run 36v/16a
continuous even in PWM mode. Suspect heat
sink and fan would make it last a lot longer. Doesn't look that much different than say www.mpja.com (http://www.mpja.com) item 4057MD at $15,
rated at 10a (which would also probably last longer with a bigger heat sink). Steve

11-14-2004, 08:58 PM
My 12vdc wiper motor with additional gear reduction kept blowing 10A fuses when heavily loaded. You may want to concider "more beef" than a 10A controller.

Power window motors generally run through a 20A circuit breaker. Just my $0.02.

11-14-2004, 09:05 PM
I ran real small 50oz.. steppers with a pc power supply.. years ago.. Not real sure how good the newer ones are..

THE old standby..a transformer out of a old battery charger, a bridge rectifier cube from radio shack and a capacitor.. Limit current though a sliding resistor (amplifier load test) and away you go.. rough and ready and cheap..

OR get a drawing for a pcb using a 556 (dual) 555 timer, one side generates frequency, otherside modulates pulse width.. You can make your own speed control then..

OR,,, pay like I did $35 for a small new industrial dc drive, hook 120vac to it a speed pot and a direction toggle and use a small brush type 90 volt motor.. another $15 plus shipping for motor.. there ya go.. it'll outlast the machine..

OR, go buy yourself some servos, buy a rutex servo drive, build a real powersupply and ... HARUUUMPH... make a real cnc...

David Cofer, Of:
Tunnel Hill, North Georgia

[This message has been edited by ibewgypsie (edited 11-14-2004).]

11-14-2004, 09:56 PM
Geez...I hope this works...I bought the one off Ebay today.
Ken..I need a really slow speed setup and after fooling with DC motors all day was going to use a wiper motor using the low speed with an extra 6 to 1 reduction using bicycle sprockets/chain. The power window motors are way too fast IMO. The wiper motor seems to have a lot more torque on startup as well.
Steve...$15...(sigh) this ALWAYS happens!
David...Ya...I hear you...somehow knew you'd bring up the CNC deal....yer probably right...well, no, you are right! But for now I want to learn more about this stuff and this seems like a good starting point...or not? Thanks all for the info!
BTW...ibew...I joined a CNC bb yesterday. Wow...what a steep hill that's going to be! I spent til 3am reading articles/posts in there last nite. Now I really appreciate you and some of the others that have a good grasp on CNC setups. I can turn on a light switch fairly well and have changed a few sets of flashlight batteries with good success so this should only take a couple decades to sink in...lol!

[This message has been edited by torker (edited 11-14-2004).]