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Has anyone used a computer power supply to power a track? These supplies put out +12, -12, 5, and -5 volts DC and between 3 and 8 amps depending on make. If you have an old computer, it might make a cheap replacement to the common wall brick.
 

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Brian Ferguson
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Older supplies, such as found in a 286, do not yield very much current on the 12-volt output. Usually no more than 1, maybe 2 amps, so they aren't a great improvement over wall-wart supplies. The 5-volt outputs are much more robust, with 10 amps or more being common. That makes them very useful for lighting and timing sensors, etc.

Newer supplies often have circuitry that reacts negatively to the wild fluctations in demand that slot cars produce even though the 12-volt outputs may typically yield anywhere from 3-10 amps. Some supplies will even oscillate between on-and-off or just plain get flaky when the load on them swings as it will in use with slot cars.

It depends on the specific supply, and there are literally hundreds of different ones out there, but it is hit-or-miss as to whether you can successfully use one.

By all means, try it if you have one laying around. But don't expect it to perform like a proper power supply.
 

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I've run PC PS's for quite some time now, no problems at all detected.

A problem is that they selldom actually give the stated 12V, but a silly way seem to work... (No, I wont tell, because it's not a way to do it that is "safe").

Anyhow, get a few not to old PS's and use the one giving the highest voltage.
And at 5A it's plenty of amperage to use.

Personally I'm going to abondon this set-up that I've used for some five years by now.
In favour of a power supply that will give each lane the same net effect available. Yes, a set amount of volts and a set amount of amperé.
What I hope to gain from this is an end to endless trouble with getting engines different profile to work together in an aimable and competetive way.
And a PS my fianchée built during classes seem to have the needed set-up...


More to come, for sure, on this...


/Erik
 

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Al Schwartz
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One of the issues with switching power supplies (all computer supplies are in this category) as opposed to linear (transformer operated) supplies is that switching supplies often expect and need some minimum current draw to maintain regulation. You might be able to "trick" one into behaving correctly by putting a permanent resistor, e.g. 120 ohm, 5 watts, across the 12V leads. this will pull 100 ma and should kick the supply into the regulated region. I don't know if a similar cheat would need to be applied to the 5 volt side.

EM

ps. the resistor will be dissipating 1.2 watts - a 5 ohm part will get warm but should hold.
 

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Indeed, but when running HO sliders there was no big deal here.
Trying to get NC's, Mab-S, V12's etc to work together is quite another thing.

And when I found a way to cut both volt and amperé the rest was simple...
 

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Brian Ferguson
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Even hot 'HO' motors will tax a PC supply. EM's trick will help, but reverse EMF and the constant demand fluctuations will tend to affect cheaper supplies. I played with this stuff for years and gave up, eventually building a massive linear supply that I still use.

Good supplies aren't cheap, but now you can get one for about the price of two or three cars, gain the advantage of variable output voltage.... and never worry about power again.... ever!
 

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Variable ouput voltage isn't my concern, what concerns me is to get a a set amount of effect available to each lane. Ie 12v 0.7A, for example, as a max outage. Thereby making engines "the same".

And a neat trick EM, I'll try that too.
 

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Thanks to all who have responded! I "found" new switching power supplies available from an electronics surplus vendor in California that offers 12vdc at 6 amps, for 10 bucks. A case of 8 for 72 bucks. That is the incentive.
I'll get one to test, and if it works out, then get one for each lane. Rather have a new power supply for each lane, AND the three new cars to run on said lanes!
I have a nice Pyramid variable to use for the test track, but rather not have the lanes all pull from the same source, and the surges that come along with. Dan Wilson
 

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QUOTE (Ecurie Martini @ 8 May 2005, 22:41) <{POST_SNAPBACK}>One of the issues with switching power supplies (all computer supplies are in this category) as opposed to linear (transformer operated) supplies is that switching supplies often expect and need some minimum current draw to maintain regulation. You might be able to "trick" one into behaving correctly by putting a permanent resistor, e.g. 120 ohm, 5 watts, across the 12V leads. this will pull 100 ma and should kick the supply into the regulated region.

Is that only for the ATX powersupplies or also for the old AT ones.
For me it worked perfectly, but maybe I was just lucky.
I assumed that the regulation and filtering for the 12 Volts is so much better because its designed for Computer devices. With the one I used i couldn´t measure any fluctuation. And its plenty of power.
 
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