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Calling All EE's!

Started by JAS6377, February 17, 2015, 06:04:07 PM

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JAS6377

Or those with some decent experience regarding PSC motors.

I currently have a 1/25 hp PSC motor that I'm planning on using in my senior project to rotate a scale-sized crane's boom. It won't require much torque, so this should be able to handle it. If not, it was free anyway so it's no loss to me. Only to my parents who had to pay to have their furnace motor replaced (that sucked).

Anyhoo, what I'm planning on doing is wiring it up to a deep-cycle marine battery via a power inverter, followed by a rheostat for speed control. Beyond that is where it gets sketchy for me. I'd like to include a method of reversing the motor direction via relays and a 3-way toggle switch, or something similar. I've been reading up and found that this is possible by reversing the winding leads.

Any insight into how to reverse this little guy?

For reference, here it is. 2 power leads (one I'm assuming goes to the cap?), ground, and a 4mF run-capacitor.




EDIT: To clarify, the impeller in the furnace blower cracked, so my parents had to replace the unit. I then salvaged the motor from the old unit that was going to be thrown away. Just in case anyone read that part wrong. I don't generally go around the house tearing things apart lol.
Blue 2004F with some fun stuff
Lunchbox, 22.5/65/147.5, Jardine, 17/39, R6 throttle, R6 shock, .85 springs, GSXR1100 rearsets, Clubmans+Rox 2" risers, T-Rex sliders, flush mount fronts, integrated LED tail, integrated LED fronts, HID Projector, blue gauge LEDs, 12V outlet

And 96.5% more wub wub

pliskin

#1
 :icon_question: something tells me you have a one-of-a-kink hobby. I say yes to your question. Go with that. Don't listen to me. I have no idea what I'm or you are talking about :dunno_black:

R u putting a crane on a GS? Shoot a furnace blower motor would really give it boost
Why are you looking here?

JAS6377


Quote from: pliskin on February 17, 2015, 09:25:32 PM
...
Shoot a furnace blower motor would really give it boost

Funny that you mention that. My first thought when I saw it was, "Man, that looks like a big plastic turbo" lol.
Blue 2004F with some fun stuff
Lunchbox, 22.5/65/147.5, Jardine, 17/39, R6 throttle, R6 shock, .85 springs, GSXR1100 rearsets, Clubmans+Rox 2" risers, T-Rex sliders, flush mount fronts, integrated LED tail, integrated LED fronts, HID Projector, blue gauge LEDs, 12V outlet

And 96.5% more wub wub

sledge

#3
To alter direction of a 1ph motor you need to reverse current flow thru the start winding OR the run winding but not both of them together. Higher resistance circuit will be the start winding. Problem is those little motors don't always have access to both ends of both windings, the common connection between the run and start windings and the phase or neutral is usually made internally within the winding and is completely inaccessible and looking at the pic I think I am right........plus your idea of governing speed with a rheostat. It doesn't work well with AC. Drop the voltage much below rated and it will stall and overheat.

This is what you have got......


See the connection between the run and start windings and the neutral?.....if that is made within the winding you are screwed and given that its a fan motor which will only ever spin in one direction throughout its life it almost certainly will be.

Want my tip......get an old 12VDC wiper motor from a junkyard, one with and an ungrounded case and ideally one with a permanent field and work around that. You will be able to run it off a car/bike battery (don't forget the fuse) change direction easily enough by reversing current flow through the armature with a DPDT switch and you WILL be able to govern speed by varying the armature voltage with a rheostat. Only down side is you might loose torque at the slow end.

Biggest plus point of going with 12VDC and perhaps the most important............you aint feckin` about with mains voltages!!!


Almost forgot......this is how to do it with a DPDT switch.


JAS6377

#4
Thank you, sir. I appreciate all the info. We do have a 12VDC motor on the shopping list, but we also have a very tight budget. I just figured it was worth a shot to be creative and see if we could save some money.

I prefer DC anyway. It's so much simpler to work with lol.

Edit: After looking into it, we're going to go with the 12VDC motor that we initially planned on using. It's a 12V Milwaukee drill capable of 23 ft-lb of torque. However, I am wondering about the starting torque. The only thing the motor needs to do is overcome the static friction of a large bearing, which is minimal at best (we calculated about 12 ft-lb with a 200 lb load, which is the designed maximum). It would require much less torque after initially moving the boom. Is there a way, perhaps through a capacitor wired in parallel with the potentiometer, to give that initial small burst of torque to get the boom moving, while still maintaining the desired RPM?
Blue 2004F with some fun stuff
Lunchbox, 22.5/65/147.5, Jardine, 17/39, R6 throttle, R6 shock, .85 springs, GSXR1100 rearsets, Clubmans+Rox 2" risers, T-Rex sliders, flush mount fronts, integrated LED tail, integrated LED fronts, HID Projector, blue gauge LEDs, 12V outlet

And 96.5% more wub wub

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