Thread: AC Power Souce for DC Vent Motor???

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I have some of those 12v DC vent motors. Am I able to use a 12v AC wall wart power adapter for these. They put out 12v AC, 4 amp.

No. Do not apply any AC voltage to a DC motor.

Look at the wall wart carefully. Make sure it says 120 ac, that is the input voltage and if it is dc it will say output 12 dc. If it is an ac adapter it will not work.

Yes, you definitely need a DC output for the vent motor. I would think AC would fry it.

Yes unfortunately I went to a thrift store today and got three 12v 3 amp adapters, but didn't take notice that all three are AC output. At least I only pad $3 for the lot. A lesson learned for $3 is a good value I think.

Ryan, it's really not that big of a problem to fix. You can order online, or simply go to an electronics parts supplier and get a bridge rectifier. Or, build one yourself out of 4 diodes and that will convert the AC output of the wall wart to DC. In fact, building your own is usually cheaper than buying a pre-assembled bridge rectifier. Though less convenient, obviously. But, that is all you need for powering a motor.

Schematic for a simple bridge rectifier:

The issue I was trying to resolve was that my vent motors seem to be struggling to carry the load. I have one I use on a tombstone, which lifts only a very light weight thin plastic skull and a 30"piece of 1/2" PVC. At most a pound total and it still struggles. I also use two of them linked together through a belt & pulley to lift my average weight FCG. In both cases they really struggle. I had only been running a 12V 500mA wall wart on each motor. Someone suggested I wasn't running enough amps, so I purchased ones with at least 1 amp each. Obviously the wrong kind, so I went out today and purchased some more from a thrift shop, all 12v DC 1 to 1.5 amps each. This also doesn't seem to correct the problem. The motors still seem to be struggling. Any suggestions?

I wouldn't suggest them for an FCG, unless it's one with a short arm on the motor. Think of it like a lever, the motor as the pivot point of the lever. On an FCG, that is quite a bit of load at 10" of length for the pivot arm, even for a exceptionally light ghost attached to it. Don't worry too much though, they always sound like they are straining under a load of any sort that haunters would put them through. All of mine do, especially in my wallbreaker ghost!

Btw, any wall wart 400 ma or above is sufficient to power one of these motors. If they are pulling more than, then they run into their stall rating and stop. Burning up the brushes in the motor is the result if allowed to stall under power for long. As long as they don't slow down to a literal crawl, your fine.

Just a guess but I think it's your linkage more so than the motor. Try waxing your lines on the FCG and as for the tombstone peaker you are probably creating a bind in the O part of the linkage that the PVC runs through that's causing the problem.

Madmax, last year I noticed the lines dragging through the I hooks so I used a little valoline on the fishing line. It helped, but I ended up replacing the eye hooks with little pulleys, so there's no drag at all. Also, there's no bind at all between the eye bold and the PVC because the eye bolt rotates freely along with the PVC so they are always in line with each other. The tombstone popper works well enough. I've been using the same motor on that for three years, but from the beginning you could hear the motor winding down on the up stroke.
The FCG works, but floats down at one speed then floats back up much slower, which is quite noticeable. If it weren't for the two speeds she would look very organic rather than mechanical. I guess I should just spend the $50 and buy a proper motor got the FCG.