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Discussion Starter #1
I aquired 2 computer power supplies. I am wiring up a MIB and some other props with wiper motors. I figured out the wiper motor wiring and they worked fine with a 12V battery hooked up. I jumped the green wire on the power supply harness to power it up and it turns on.My power supply looks just like scary terry's. The wiper motors turn on , but goes to slow, when I hook them up to the 5V side of the harness but when I hook it up to the 12V side, it shuts it down.
Any help would be much appreciated.
Thank you
 

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Discussion Starter #3
Im Still stumped. I put in the resistor as stated in the tutorial. it worked great at first then i turned it on and off a couple times and now its doing the same thing it did before the resistor was installed.
PLEASE HELP!!!!!!!
 

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Undead Handyman
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Someone check my math, but I think you need a resistor thats rated to handle 112.8 watts if you are drawing 9.4amps and 12volts. Man, high-school electronics suddenly seems so long ago. Your 10watt resistor is probably fried.:confused:
 

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Discussion Starter #7
OK, So do you have any idea what I could do? I just looked at the motor and it doesnt say what the amps are. I thought It was 9.4 but that was a different one. Its just a small wiper motor from a ford escort. Did I waste my money on these power supplies?
Thanks
 

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Undead Handyman
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Ok, I did some checking on Ford Escorts and they generally have 20amp fuses on the wiper motors which means they probably draw 14-16amps. If thats correct you now need a 10 ohm resistor rated at 200watts. Anybody care to check my math....please.
 

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Discussion Starter #9
Thank you for doing the research. I dont think that such a thing exists. I googled it with no joy. So, if thats the case, how does everyone run wiper motors with a Power supply from a computer?
 

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Undead Handyman
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I think my brain is finally into the correct gear. Your power supply is only able to safely provide 12amps at probably 12-19volts. Your motor needs lets say 16amps. The reason it works slowly on the 5volt side of the harness is because when the voltage is lowered the amps are increased. Even if you aquire a 200watt (pricey) 10ohm resistor you will be drawing more amps than your power supply is designed to handle and the resistor and the power supply will both get HOT! I would suggest a motor that uses significantly fewer amps.
 

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Discussion Starter #11
I guess the ford $10 wiper motors were not that good of a deal. Lesson learned. Thank you again for all of your help.
 

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I don't know my electrical engineering stuff like I once did but... I think you can solder resistors together (parallel? series?) to create the amount of resistance you seek. Talk to some one who really does know electronics and circuits. Maybe they will chime in soon. Don't toss your wiper motors yet.
 

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I don't know my electrical engineering stuff like I once did but... I think you can solder resistors together (parallel? series?) to create the amount of resistance you seek. Talk to some one who really does know electronics and circuits. Maybe they will chime in soon. Don't toss your wiper motors yet.
paralle - decreases the resistance.

series - increases the resistance.
 

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I use four wiper motors in my display and have never put any resistors in the circuit. I even run two motors from the same power supply.

I would check another power supply.
 

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I use four wiper motors in my display and have never put any resistors in the circuit. I even run two motors from the same power supply.

I would check another power supply.
Same here. I typlically use the 5v supply to reduce the RMPs on the motor - no motor or supply burn out. As long as the supply has a load ( I believe on the 3v wire ) then it will turn on. I do not use a resistor. If needed a stop lamp from a car works just as well.
 

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Discussion Starter #18
DanoNJ, I have a couple of really good friends who live in Monroe. Wayne Stark sound familiar? Anyway, The motors run great on the 5V line and it was working perfect on the 12V side to. I dont know that much about resistors, but I think the resistot is fried. It is acting as if it were not even there. I can use the 5V side for my witch's cauldron hangman, but I wanted the speed I get with the 12V for the MIB.
Thanks again.
 

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Try another 12V lead from the power supply. If the motor works on 5V, it should work on 12V.

BTW, are you thinking the resistor is gone in the motor or the power supply?
 

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Discussion Starter #20
The resistor that has to be put on the 5V side of the power supply to simulate a load. It is the 10 ohm 10 watt resistor that has to be installed during the convertion. I agree, I can run as many motors as I have off the 5V leads, but it is the 12V i desire. I tried running it off of one of the other leads and it does the same thing. Once I hook up the wiper motor it shuts down the power supply. I believe what "walking corpse" said.. The motors I bought, from the ford escort are no good in this application.
 
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