AC to DC for wiper motor!

OKAY, so I am using 120V AC power for my electric HERMS, but I am contmplating using a DC wiper motor for my water stirrer. If I wanted to do this, how do I get my 120VAC to 24VDC and connect it to this motor? Is this more trouble than it is worth? I can buy a 120V motor from McMaster Carr for $53, and it would be plug and play so to speak!

I am wondering if that motor would have enough torque under that duty? That would be something to look up. Especially if you make thick mashes. I think that question should be answered first, if it will then you should be able to get a converter off the shelf...but it may cost you ballpark the same amount.

you can get 24vdc from an old PC power supply or many laptop power supplies, some other electronics use 24vdc power cubes. Im sure you could also find something cheap online. The easiest solution would be the PC power supply, they should be able to handle any load the wiper motor might put on it and you can pull them out of the garbage all the time.

not to derail your idea, but couldn't you take apart an inexpensive box fan? It is set up for 120V AC and it has a speed control. Just mount the speed controller in a box and Oila!

Total cost: ~$10

The box fan idea has been considered, along with an ice cream maker... I like the idea of the speed control and 120V of the box fan, and the economy. I could probably get a project box from radio shack and hook that up pretty simply and make it look pretty. Have to look at CL.

The Pol said:

The box fan idea has been considered, along with an ice cream maker... I like the idea of the speed control and 120V of the box fan, and the economy. I could probably get a project box from radio shack and hook that up pretty simply and make it look pretty. Have to look at CL.

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You may need to put an inline fuse on one of the wires going to the motor. Then if the motor gets overloaded or stuck, the fuse will blow.

If you still are interested in using a wiper motor, here's some info...I'm into halloween decorating in a big way, and a lot of guys use them in their setups....Here's a good site on using them... http://www.scary-terry.com/wipmtr/wipmtr.htm

It covers the pro and cons of using different power supplies and other nifty info...how to wire em, rig up speed control and iirc even computer controlling them.

FWIW, an automotive wiper motor runs on 12vdc, not 24vdc. They will draw up to 5 amps at full speed, depending on the manufacturer.

Screw it... LOL, on someone elses advice, I am buying a cheap-o box fan and mounting the speed control in a nice 4 x 4 junction box and calling it good. I will have speed control and a cool little control box to boot. The motor should have WAY enough power to simply stir water. I am asking SWMBO if I have permission to go to Lowes and "FINISH" my brew build... again. You have to relaize that I FINISH it every 6 months. Thanks yall!

Buy a 120VAC -> 12VAC transformer or scrounge one out of a dead piece of electronics. Then use 4 diodes to rectify the signal to DC. Just a few $ and you're in business.

Well, the box fan motor idea has failed.... it failed in about 5 minutes. The motor overheats without the fan pulling air through it so quickly that you cannot even get the brew system fired up! Any motor from any fan, will fail... they are made to be cooled, and when you remove the fan, they smoke themselves. I will have to buy a much more expensive motor, but I wont have to worry about it failing.

Man, sorry to hear about the lost $ on that idea. Good to know tho. I guess a ceiling fan motor would do the same.

I wish I'd seen this earlier...I might have been able to dissuade you from the box fan idea. A wiper motor will have plenty of torque and can be powered by any 12VDC transformer capable of about 5A. A cheap automotive battery charger will work if you have trouble scrounging a PC supply or other suitable source.

I have a PC power supply, obviously, but how do I get this plug to connect to a wiper motor that will come to me with nothing more than 2 wire leads?

+12VDC should be a yellow wire. Here's a tutorial:

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

The Pol said:

Well, the box fan motor idea has failed.... it failed in about 5 minutes. The motor overheats without the fan pulling air through it so quickly that you cannot even get the brew system fired up! Any motor from any fan, will fail... they are made to be cooled, and when you remove the fan, they smoke themselves.

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Not only that, but electric motors are not meant to be run at a low rpm. The resistance through the coils is inversely proportional to the rotation rate. When you slow the motor down the resistance drops and the current flowing skyrockets. current = heat and heat = dead motor...

Motors like those used in a windshield wiper or ice cream churn spin at full speed and then use gears to reduce the final shaft speed. That has the added benefit of increasing torque.

Yuri_Rage said:

+12VDC should be a yellow wire. Here's a tutorial:

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

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Personally, I'd just roll my own for a simple load like a dc motor (or buy a power cube/wall wart), but that's a good article for the ref file. Thx for the link!

Yuri_Rage said:

I wish I'd seen this earlier...I might have been able to dissuade you from the box fan idea. A wiper motor will have plenty of torque and can be powered by any 12VDC transformer capable of about 5A. A cheap automotive battery charger will work if you have trouble scrounging a PC supply or other suitable source.

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Yep..go read the article link I posted on the use of them in Halloweem decorations...People make caldron stirring witches with them all the time. It will have enough torque to do what you want.

I am buying an AC GEARED motor from McMaster Carr. It is 100RPM and 7 in-lbs of torque. 1.6 AMP motor with a cooling fan. This, should... work.

If you take apart a box fan switch you will see that there is nothing there except some contacts that energize different windings in the motor to control the speed. You can't use that as a general speed control. It will be either ON or OFF.

BitterBeerFace said:

If you take apart a box fan switch you will see that there is nothing there except some contacts that energize different windings in the motor to control the speed. You can't use that as a general speed control. It will be either ON or OFF.

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Good to see you posting on here BitterBeerFace!