# Powersupply/transformers



## Spooky1 (Aug 25, 2008)

Has anyone tried a model train power supply (like this) to control a wiper motor or other prop motors?


----------



## spinman1949 (Jun 29, 2009)

*Wiper motor needs amps.*

When considering and power supply to drive a motor, three questions must be answered. 1. Is the motor AC or DC ? Could be a stepper motor which requires an actual driver. 2. What voltage range can the motor function within. In the case of a wiper motor the normal rated voltage is 12 volts. The motor will run slower with less and may be able to handle slightly more as well. 3. How many amps does the motor draw ? Note if you look at specs on servo's for instance, you may see amp draw no load and with load. Point being that if the motor is just spiinning by itself, the amp load is less as opposed to running windshield wipers in a heavy rain.

So now that you know the three questions, can you provide answers?

The model train controller will likely provide an acceptable range of DC voltage to drive the wiper motor, but I kinda doubt it can provide the amps. Think of the size of an HO train engine and the size the motor must be. Now consider the size of a wiper motor. Basic rules as far as motors go ? The bigger the motor the higher the # of amps it will draw.


----------



## hedg12 (Jul 6, 2008)

Most H.O. train transformers vary the voltage from 0 - 20 volts, so you'd run the risk of sending too much voltage to the motor. As far as amps go, the output of train transformers is all over the map. I've seen them from 10 watts all the way up to 320 watts. I've run a wiper motor for hours off a 5 volt 1 amp wall wart (albeit with a very light load), so finding a transformer of sufficient power to run your motor shouldn't be a problem. Most are rated in watts, so divide the wattage by 12 (assuming you're using a 12 volt motor) to get your amperage rating. One thing to keep in mind though, is you get what you pay for. A cheap transformer might put out 300 watts max, but it also might overheat after 10 minutes of running your pop up.


----------



## hpropman (Jul 27, 2008)

computer power supplies are great for wiper motors - you have 5 volts, 12 volts, and 3.3 volts with lots of amps and you can find them curbside when someone throws out a computer. Make friends with your IT techs at work they might be able to get one for you. Buy them food and you can pretty much get what you want.


----------



## Jaybo (Mar 2, 2009)

hpropman said:


> computer power supplies are great for wiper motors - you have 5 volts, 12 volts, and 3.3 volts with lots of amps and you can find them curbside when someone throws out a computer. Make friends with your IT techs at work they might be able to get one for you. Buy them food and you can pretty much get what you want.


 Yep, PC power supplies are great. They have lots of power and fault protection circuitry. If you overload the supply, it will shut itself off to protect itself and keep you from burning the house down. If you short a wire, it will also shut itself down.

Even if you can't find a used one lying around, you can buy a cheap new one for $20.00. They provide enough power to run several props at once.

I run LED spotlights, a peeper tombstone, and a FCG on one supply and still have oodles of power leftover.


----------



## Spooky1 (Aug 25, 2008)

Thanks for the advise guys.


----------



## Decrepit Desecr8shun (Aug 10, 2009)

spinman1949 said:


> When considering and power supply to drive a motor, three questions must be answered. 1. Is the motor AC or DC ? Could be a stepper motor which requires an actual driver. 2. What voltage range can the motor function within. In the case of a wiper motor the normal rated voltage is 12 volts. The motor will run slower with less and may be able to handle slightly more as well. 3. How many amps does the motor draw ? Note if you look at specs on servo's for instance, you may see amp draw no load and with load. Point being that if the motor is just spiinning by itself, the amp load is less as opposed to running windshield wipers in a heavy rain.
> 
> So now that you know the three questions, can you provide answers?
> 
> The model train controller will likely provide an acceptable range of DC voltage to drive the wiper motor, but I kinda doubt it can provide the amps. Think of the size of an HO train engine and the size the motor must be. Now consider the size of a wiper motor. Basic rules as far as motors go ? The bigger the motor the higher the # of amps it will draw.


 w/o doubt. You will certainly end up w/ a burned up train controller. Even if you used one for "O" scale(Think Lionel trains). They cannot handle the draw of a wiper motor. And voltage limiters for wiper motors are available cheap thru JC Whitney under variable speed wiper module(some even come w/ a variable time delay). Cool huh? Y waste precious design time when what you need is available for next 2 nothing costwise...use a computer power supply as they will supply all the power you need and have extra outputs that can be used 2 drive leds,pneumatic solenoids and more.


----------

