Thread: Wiper motor power supply question

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I have a power supply left behind by the cable guy. It says the DC output is 12v and the amp output is 2.9A. I wanted to do a tomb stone peeper type of prop. Where it pops up over the top as it rotates on the motor. Will this 2.9 amp output be enough? I see the lap top power supplies that Monster Guts sell puts out 5A. Not sure if this one will work. Thanks for any help.

Under no load it might be ok, but the moment you put a load (any resistance) on it you will have problems.

As long as the moving mass isn't too heavy you'll be fine. I have one with a wiper motor that uses a blucky skull & it runs fine with a 1 amp wall wart.

You may find 12v will make the motor too fast. I stepped down to a 4.7ish (I forget if it's .7 or .9) wart to get a slower motion for my stirring witch. Amps will be your limiting factor for torque.

Running a wiper motor at the 12 volts should be fine with 2.7 Amps. I have one in my MIB that is a 3 Amp supply and it has been working for years and the lid is quite heavy (approx 10 lbs) with the chains on it and I haven't burnt out that supply yet or had any issues with it. But you'll find 12 volts on a wiper motor at the slowest speed to be too fast for a peeper. I built a peeper last year using a wiper motor and stepped it down to the 3.3 Volts from a computer power supply. The problem running the motor at the lower voltage also meant it required more Amps. Burnt out the first power supply which had 18 Amps on the 3.3 Voltage. Ended up using a computer power supply with 27 Amps on the 3.3 Voltage and it ran fine after that. I tore the peeper apart this year and replaced the wiper motor with this one. Runs at a perfect speed for the peeper, uses a 12 volt power supply and is working fine with a power supply less than 1 Amp.

You can slow the motor down with this - http://store.qkits.com/moreinfo.cfm/MX033 - 19 bucks and works great. Goes in-line between your power supply and your motor using regular spade type wire connectors. Allows you to dial down the speed all the way to zero rpm's without any loss of torque.

I didn't realize the 12v would be too fast. I have a computer power supply I was thinking about converting but I thought it would less work to use this. You guys gave some great ideas too. But I wonder if the easiest solution would be one of those wal warts that has adjustment for volts on it. How much does it usually cost to convert computer power supply?

Originally Posted by gr8johnson

I didn't realize the 12v would be too fast. I have a computer power supply I was thinking about converting but I thought it would less work to use this. You guys gave some great ideas too. But I wonder if the easiest solution would be one of those wal warts that has adjustment for volts on it. How much does it usually cost to convert computer power supply?

Not too much really, just depends on which power supply you have. Most of the ones I have found & use jump a wire with a switch between a green & black neg wire in main harness & you have power,
cost:
15 - 20 amp 12v switch: several dollars
electrical tape-
solder or spades for attaching wire to switch-
= several dollars
& with thisain'tmayberry's lil speed adjuster he suggested, you have a better power supply that is most likely a lot better than the walwart & should handle whatever you throw at it......
plus you can adjust the speed to whatever you need it to be for the effect you are going for as for speed of prop motion !

Here's a link to a recently posted tutorial on setting up a computer power supply for use - Converting an ATX power supply - that looks pretty neat.

I wouldn't drop the volts in order to control the speed of the motor. Don't want any blue smoke coming out! Use a speed controller like I mentioned above. I mounted this controller inside the ATX power supply box so it was a nice neat package. I use it to run an Axworthy ghost wiper motor at slow speed with full torque. Haven't had a problem in 5 years (knock on wood).

Oops - Dark Lord beat me to it