# Using an ATX Power Supply for a Prop...



## Dr. Scarecrow (Mar 14, 2011)

So, with some wonderful examples set forth on our forums- I have decided to make a stirring cauldron figure prop (I have plenty of stuff around already that I can use and really only need to purchase the pvc and motors). Haven't decided exactly how it will look yet as I am getting the basic mechanics and such down now.

My main concern is that I do not want to have to power all components separately on wall warts on a power strip. I expect to have multiple LED's, probably just 2 motors (wiper and another [or maybe 2] for body motion). This in addition to the standard fogger, a sound device of some sort, and string lights for the cauldron and fire below.

I have read Scary Terry's site inside and out and done more internet digging, but am still trying to figure out if I can go with a hacked ATX power supply for the prop.

For one, there appears to be only one 12v hookup. How is this going to work if I have 2 or even 3 motors that need 12v hook ups? Same goes for LEDs- If I intend to do many, I don't know if I will have enough hookups.

From what I saw- my plan was to just solder the wiring into the correct port on the 20 or 24 pin hookup. Can anyone point me in the correct direction of further tutorial on maximizing my use of power from the ATX power supply I have? Unfortunately- I am no electrical engineer. I have extensive experience in PC system building, but its so much more structured and "plug and play" than this....

I will start a thread when I begin the project. I am thinking Sundays with football on in the background is going to be my most productive time this season...


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## corey872 (Jan 10, 2010)

An ATX power supply should be ideal. All yellow wires will have 12V, blacks are ground, reds are +5V and oranges are +3.3V. Plus all the molex connectors should have yellow, red and black for multiple hook-ups.

Most older supplies you'd find in scrap / for cheap would still have double digit amperage on all those lines. - ie a 300W supply would probably have around 15A per level. That would easily handle 2-3 small electric motors on the 12V rail, about 1,500 LED's (ie 750 series groups @2.5V) on the 5V rail and another 750+ on the 3.3 rail. So that should be plenty of power to make the witch bubble, stir and twinkle all at once.


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## hedg12 (Jul 6, 2008)

ATX power supplies are pretty easy to modify - trust me, if I can do it, anyone can!  I covered a couple of different ways to do it on my blog, although those might not be the best examples. Google will turn up many other how-to's.
Your main concern - once you get the power supply modified - will be the supplies ability to power everything you want it to. Most power supplies list the max amperage available off of each "rail", or discrete output, on a label. The key word here is max - most supplies will only sustain these levels when only that rail (voltage) is being used, and then only for a short time. In other words, if a supply says it will output 7 amps max on the 12v output, it will only do so if the 3.3v and 5v outputs don't have an appreciable load connected, and then only for a short time.
Wiper motors represent a very dynamic load to the power supply. In other words, the amount of current needed to run the motor varies quite a bit, and is affected by the physical load on the motor. If something binds up in your prop & puts a heavy drag on one of the motors, you could end up burning up the power supply. That said, I've run a wiper motor powered tombstone peeper all night for several years on a 1 amp wall wart with no problems. I would suggest investing in some inline fuse holders, & put a 3 or so amp fuse in line with each motor. That way if it stalls, you'll blow a fuse instead of your power supply.
If you're running LEDs off the same power supply, you might think about using the 5V output for them if you can. You'll waste less power as heat.


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## Haunted Spider (Sep 6, 2010)

As Corey has stated, you need to look at a few simple things for your power supply. First is the Amp level. I have two at home and one is 13 and the other is 16. Both will power alot of stuff. A wiper motor pulls 3A so you could power 4 of those alone. 

Second thing to do is to measure the actual output of the wires. All wires of the same color will be the same output but they may not match what you want close enough. I have one power supply that puts out 11.85 V and the other puts out 10.83V. You need a multimeter to test this. They cost 15 dollars for a cheap one on amazon that includes batteries already. Make sure the Volts are close for what you need. Too much deviation and it will throw off the device you hook to it, especially LEDs because of the resistors.

Once you find out you have a good supply, remember that each wire Yellow 12V etc. holds the same current. Cut the wires with the supply off and solder your connection. You could ahve up to 20 yellow wires depending on the supply which would give you 20 connections, or 10 if you doubled the wires. It is your call. Just add up the Amperage and make sure you are not going over. 

The other great thing about the power supplies is they have a safety built in for fault protection. They are very safe for LEDs and small motors. 

I did see you want to include sound and motion in your prop. You may entertain the idea of a prop controller like the Nerve center from Monster guts. I have heard rave reviews on it as it controls two channels and sound for 8 different effects. I ordered one for my display a few days ago and am excited to get it. Just my two cents. Hope it helps.


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## Death Wraith (Mar 23, 2006)

I won't go into all the tech details cause I might say something wrong, but I have hacked two ATX supplies with great success. Make sure to follow all the cautions in whatever tut you follow cause you're gonna be dealing with opening up and getting close to where electricity runs.

Rather than solder wires directly into my supply I mounted binding posts on the outside of the case so I could easily switch wires year to year. I think a lot of the tuts you'll find take that approach. Here's one example of this approach:

http://www.instructables.com/id/The-Ultimate-ATX-Power-Supply-Mod-With-USB-Chargin/

On the first one I did I only installed a ground post and one 12v post. On my second I put in one ground, one 12v, one 5v and one 3.3v.

You could also use barrier strips with jumpers to distribute the power.


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## Cole&Jacksdad (Jan 20, 2011)

I pulled one out of an old computer today. I understand the green has to be spliced to one of the ground/black wires. I have several yellow, red and orange wires. Can I run several props at once? Example, so I have a pneumatic prop that has two 12 volt solenoids and an Arduino controlling the prop. Would I need another 12 volt source or since there are several yellow/12 wires will it work? I believe the red/5 volt should be able to power the Arduino.


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## hedg12 (Jul 6, 2008)

You should be fine running 2 solenoids and an Arduino.
All the wires for a given voltage are common, so it doesn't matter which yellow wire you use (yellow for 12V, red for 5V, and orange for 3.3V.) You can tie multiple 12V loads to one yellow wire, or use different wires for different loads. As long as you don't overload the wire (not likely) the power supply doesn't know the difference.
There are some newer power supplies that have multiple 12V rails, but the color assignments are the same.


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## Cole&Jacksdad (Jan 20, 2011)

This is going to save me from several wall warts. Great forum!


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## Haunted Spider (Sep 6, 2010)

Cole, Just make sure when you twist several wires together such as 2 or 3 yellow that you test it with a multimeter and make sure the output is correct. There is always a chance that you have multiple rails and would then change the voltage. I always check the voltage before hooking to a prop. Much cheaper mistakes that way.


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## Dr. Scarecrow (Mar 14, 2011)

Truthfully- I don't know if I have the time or ability right now to fully convert the power supply into a reusable hookup. I'd love to- but I can barely get an hour to go to the store to purchase the stuff I need these days.

While I'd love to go the Monster Guts ready to go route (which would be much simpler and easy)- its pretty cost prohibitive. Same with the nerve center- I'd love to use it, but just can't this year. Darn budget......

I have an ATX just sitting in my closet along with a bunch of wire, connectors, etc. If I can cut, crimp and go for a period of 3 nights when this guy would be up. I'll be a happy camper. So I guess- is that doable??

Also- I think I just realized, using a Monster Guts wiper blade in the 12V hook up will make it ridiculously fast. I think I would just hook it up to the 5V instead and call it a day. I'm not going to need much power/ torque for the stick and foam parts I intend to use.


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## Haunted Spider (Sep 6, 2010)

Remember there are high and low settings on the wiper motor. You should be able to get 6 different speeds depending on the high low setting and if you use 12, 5, or 3.3 volt. Any voltage will run the motor, it will just change the speed, hence the speed controller monster guts sells. 

The ATX should work great for the 3 nights. As someone else suggested, maybe put an inline fuse in just in case. they don't cost much but will help in case of a disaster.


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## The_Caretaker (Mar 6, 2007)

Also keep in mind that a motor takes more amperage when it starts than to run it continuously so if you are starting and stopping the motor you will have to take that into account on how many you can run off one power supply


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