Question for Websterz

[Bill S]

In a recent post you mentioned using a hacked computer power supply on your x-axis power feed. Could you fill me in on a couple of things? I just hacked a 250w ATX PS and installed posts for +12v, +5v and +3.3v. I also installed a load resistor. Multimeter readings show that I have power at the stated voltages. When I hook up the motor (Dewalt 14.4v cordless) directly to see if it runs, the motor doesn't spin at all and the power trips off. According the the specs on the housing it should have 9a max in 12v mode, which should be plenty. First, what watt PS did you use? and did you try to run the motor direct? You stated you are using a PWM controller, now I'm wondering if that is my problem. Any insight you have will be helpful.

Thanks,
Bill

 

[Bill S]

I've gotten a little further along with the PS, I hooked the drill motor up to the 5v post and it would run, albeit a tad slow. Using the DPDT switch I have wired it would switch foward and reverse okay, but only if I stopped in the off position first. If I switched without pausing it would trip. I reread the info on the web page where I got the hack instructions from and the author said that some PS's are prone to do this under load. He also shows how using the ATX12v2.0 PS you can get quite a bit more power, which I am going to look into. Here is the link to the page for anyone interested.

web2.murraystate.edu/andy.batts/ps/powersupply.htm

Bill

 

[websterz]

The PS I used was a 350 watt model. I added a 10 ohm resistor on the 5 volt rail to give a constant load, and then for good measure I also installed a 12 volt 1 amp LED as a power on indicator. Going instantly from forward to reverse will trip out my rig too, I just learned to be careful and not do that. ;D Here is a link to the PWM I use.

http://www.amazon.com/dp/B000WYAN92/?tag=skimlinks_replacement-20

If you go this route be sure to put the DPDT between the controller and motor, NOT between the controller and supply. The controller is very sensitive to polarity changes and you might let the magic smoke out of it.

 

[Bill S]

Thanks for the info. Are you taking power for the motor from the 12v? Also, can you get decent speed for rapid traverses?

Bill

 

[websterz]

Thanks for the info. Are you taking power for the motor from the 12v? Also, can you get decent speed for rapid traverses?

Bill

Yes, I am using the 12v rail to power the drill motor. Here is a video of the set-up in action.

http://s797.photobucket.com/albums/yy258/websterzdesign/?action=view&current=100_0471.flv&newest=1