[foamcutter]

Hi all,
I am looking for a circuit diagram for a DC motor speed control. I am trying to control a 120VDC Permanant Magnet motor, 2 HP at about 12 amps. I want to be able to use 120 VAC input and be able to control o to 120 VDC. Any ideas? Thanks Ron

[Al_The_Man]

Ron, Does the motor have a tach? Because one option would be if you can pick up one of the Westamp A662 servo amps of off ebay, they used to be a regular item by a couple of sellers, they used to go for about $35.00 each and were good for up to 6hp 120vac input.
They made good spindle amps for cheap.
Al

[foamcutter]

Al,
No tach on the motor. I have been looking on ebay. All the motor controllers I have seen so far that are 120 VAC input only go to 90 VDC output. Anything over 90VDC output require 230VAC input. I'm trying to avoid going to 230VAC input. Ron

[Bloy2004]

Try this item:
http://www.surpluscenter.com/item.as...tname=electric

I have two of these....one for the lathe, one for the mill spindle of a 3 in 1 machine( along with two 130 volt DC motors from same site). There is also a pot for variable control(extra) listed on the same page. I haven't hooked anything up yet but if the original AC motors begin to fail, I will begin retrofitting.

[foamcutter]

Bloy2004,
Thanks for the link. I think one of those may just do the trick. Ron

[bunalmis]

You can use light dimmer and bridge rectifier.
(May be need small modifications.)

[foamcutter]

bunalmis,
I am looking at pulling a max of almost 12 amps. By using a light dimmer I think I would probably need to change the scr's to bigger ones to carry that much load, right? Do you have a diagram of a setup like this? Thanks Ron

[ccm]

I'm almost in the same boat, ac source but needed DC output...what I came up with .... I have an ac variac that I've put a bridge rectifier across the output along with a cap to clean it up alittle. I don't have the treadmill motor yet, but I've used the same rigging before and works pretty decent. The output I'm guessing is going to be around 125 to 135vdc @ approx. 15amps.

my .02...

art

[bunalmis]

You can use 16A scr or triac for 12A aplications.
Gate drive circuits dont need any modification.

example links (i dind test this circuits)

http://members.tripod.com/xexorz/sch...orquectrl.html
(You can try this circuits)


http://home.maine.rr.com/randylinscott/aug99.htm


http://www.redhouse.force9.co.uk/dex...e/electr~1.htm
(this circuit need rectifiers)