# Cauldron stirrer - power supply?



## Devils Chariot (May 23, 2007)

5V/8A, 3.3V/4A, 2.5V/2A POWER SUPPLY










Link to product page.

Would this work to drive my wiper motor? I bought a 12v 1.4 amp ps and this rotates way too fast. If I understand it right I need to keep the amperage high, but lower the voltage to reduce the speed of the motor? 
The lowest voltage on this still keeps 2 amps, so I THINK it MIGHT work, but I don't know square 1 about electronics.

my thread about the motor wiring.
The motor in question is this one: dcm-249 from allelectronics


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## TommaHawk (Sep 18, 2007)

Yes, that should work fine.

And you're right about the volt vs. amps. Fewer volts will drive the thing slower, but it will still need enough amps to work properly (motors draw the amps they need).


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## bradbaum (Jul 26, 2008)

Voltage and current (Amps) are inversely proportional. That means when the volts go down the amps go up and vice versa. But that supply with the 8A at 5V should work fine, I would be a little concerned about the 2.5 at 2 amps, but try it and see, the current the motor draws depends on the load the motor is under.


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## Devils Chariot (May 23, 2007)

thank guys for the input. Considering how affordable it is if it doesnt work for this it will work for something else. Quick question. Can i ever have too many amps since you said the motor wil only take what it needs?


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## Dr Morbius (Sep 21, 2004)

YOu can never have too much available current.


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## Eon (Apr 23, 2007)

Not trying to plug a vendor or anything, but I just saw that Monster Guts has a variable speed power supply / controller specifically for wiper motors. They call it the PaceMaker. A little bit pricey, but if you want variable speed control, it looks like a pretty cool solution. 

And, from my experience, they are great to do business with. (shameless plug)


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## Scottzilla (Jun 13, 2007)

Just wanted to point out that the inverse relationship between voltage and amps doesn't really apply here. The resistance of the motor remains the same, so ohms law tells us that if you cut the voltage to the motor the current it draws will also drop (it is doing less work by going slower, so this makes sense).

If you cut the voltage in half but expect your load to do the same amount of work or give off the same amount of light (same wattage) or whatever then your current draw will double.

That's why a 100-watt bulb in your house draws about .8 amps but a 100-watt fog light in your car draws a little over 8 amps.

The bottom line is that you don't need to worry about finding a power supply that provides more than the motor specifies because you are running it at a lower voltage.


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## Devils Chariot (May 23, 2007)

good to know guys. Can wait to get back to that project!


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## Fiend4Halloween (Aug 28, 2008)

Hey Devils Chariot, ever thought about using an old turntable for your cauldron stirrer? I use a turntable that I got at a garage sale for $10. Put it in the cauldron,connect the end of the staff, or whatever the witch is stirring with, and attach it to the spinning part of the turntable. I got lucky and the one I bought has a speed adjustment and as the table spins, the witch stirs at a medium to slow pace, looks really cool. Just a thought. Good luck.


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## Skeletons in my closet (Sep 25, 2007)

Eon said:


> Not trying to plug a vendor or anything, but I just saw that Monster Guts has a variable speed power supply / controller specifically for wiper motors. They call it the PaceMaker. A little bit pricey, but if you want variable speed control, it looks like a pretty cool solution.
> 
> And, from my experience, they are great to do business with. (shameless plug)


I agree that MonsterGuts is the way to go, especially for ease of wiring or not knowing what to get. They have 2 different power adapters for wiper motors for under $20, and I recommend the "Quick Connect" to simplify the wiring completely. Here's it's link:
http://www.monsterguts.com/electric-motors-for-props/quick-connect/prod_103.html

You can even get the motor, power adapter, and quick connect in a kit for about $36.


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## dionicia (Aug 4, 2007)

I agree with the quick connect. Also, scary terry has a brief explanation on the workings of a windshield wiper with the power supply. http://www.scary-terry.com/wipmtr/wipmtr2.htm

Monsterguts sells a 5 volt power supply that will help to slow it down as well. I used it for my Grave Poppers and my FCG. Gonna use one for my Cauldron Stirrer as well. Still need to pick up a big plastic cauldron. Might get a big plastic laundry bucket and paint it black.

Good luck.


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## psyko99 (Jan 11, 2008)

I agree that the Monster Guts power supplies are the easiest way to go, especially if you are weary of wiring electronics. However, I'm using a PC power supply this year. Here are a couple of links.

http://www.instructables.com/id/ATX-->-Lab-Bench-Power-Supply-Conversion/

http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply

There are several other how to's out there. The basic ones will get you +5 v, +12v, -5v, -12v.

But if you are skittish about wiring, go with Monster Guts.


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