Using Computer Power Supply

[jefelectric]

I have been using surplus computer power supplies to power the lighting on my layout for about 7 years with no problems.  You have to do a little modifying to get the best results.  I am not going to go into detail as my theory is if you don't know what you are doing with these, you shouldn't be doing it.  Most XT sytle power supplies will provide about 7 or 8 amperes at the 12 volt output.  Which will power quite a few lamps.  Two of them power all the lighting on my layout.

[dwiemer]

What he said!  See, I told you Bob would be the one to answer this.

Dennis

[lionelsoni]

Since you asked;-)

I am presently using a couple of Zs for the main layout, heavily modified with synchronous rectifiers.  I had been using an unregulated half-wave rectifier on one of the outputs for powering turnouts and uncouplers.  But, anticipating a block-signal scheme, I put in one of a handful of regulated DC supplies that were given away at work.  It is set to 16 volts and can supply a couple of amperes.  The uncouplers are still on the rectifier, but the turnouts have moved to the new supply.  I also use a prewar type T with rectifiers and a couple of type-81 rheostats for the elevated around-the-walls track.

I think that the 12 volts from a computer supply is probably not enough for most trains.  You have to be willing to give up the traditional whistle control also.  Controlling the voltage shouldn't be a problem.  Lionel made several models of rheostats.  You can get one for about $5 at any decent train show.

I often suggest using 24-volt HVAC relays and transformers for controlling accessories.  One of those transformers and a rheostat or two would not be a bad way to power trains.

[lckiii]

Thanks for all the info. This is my new favorite place on the web!

 

I would be using the power supply to solely power Post-War vintages;  (have run a trolley in the past off an AC adapter through some variable resistors (boy did they get hot)  Sounds like I am better off to just buy another transformer.  

[dwiemer]

One method that has been used is to take the power supply for low voltage landscape lights and use it for powering lights and accessories.  I would still go with the train transformers for running trains.  One guy on the OGR forum was having some high power transformers made, but I think any time you venture too far from intended use of products, you get into "no mans land" and may creat a hazard. 

Bob Nelson would be a good one to hear from regarding this.  He has quite the power supply set up, but he also has the know how to do it.

Dennis

[Dave Farquhar]

One major problem is that computer power supplies give DC, rather than AC. If you're running postwar that might not be an issue for you, but modern production needs AC.

The voltages you'd get out of a computer power supply are pretty limited too. You can get +12 and +5 out of them easily and depending on the vintage of the supply there might be some other voltages like +3.3. But the way the power is divided can vary, so you won't get the full wattage on each power rail. For example, one of the better 300W power supplies on the market gives 140 watts on its +5v rail, 228 watts on its +12v rail, and 80 watts on its +3.3 rail. So you're not actually getting the full 300 watts. And on some power supplies there isn't any protection to keep you from drawing too much wattage if you tap too many of the lines.

Some power supplies tell you how much wattage or amperage you get on what line (you can calculate one given the other), but most don't. So it's hard to know exactly what you're getting with a computer power supply.

Computers are what I do for a living. I can tell you that there are some power supplies that have no business powering computers (which is what they're designed to do), let alone anything else. The one common factor that I've seen in all of the notorious PCs over the years (I won't name names; there's no need) is that they all use or used low-quality power supplies.

Since I have ready access to all the surplus computer power supplies I could possibly want, I have to admit the idea did occur to me several years ago to use them on the layout for lighting and accessories. After I thought about it some more and talked to some other people about it, I scrapped the idea.

[Bob Keller]

I think the office consensus is that it is a great idea if you want to burn your house down, but probably not to run trains with.

I'm just sayin'.

[Anonymous]

Not sure the hassels of all that would be required to make them work would be worth the effort.  There are many inexpensive model railroad transformers available.  Atlas is introducing two new transformers.  The 30 watt is going to retail at $39.95 and the 80 watt for $79.95. 

Jerry

[phillyreading]

lckiii,

If you are going to use a computer power supply you should make sure that your voltage don't excede 20 volts, possible 22 volts for post war stuff, A.C. for O gauge trains, please use a volt meter!  Most of Lionel's new switches will take only 14 volts A.C. maximum to the switch.   Finding an inexpensive rheostat could be another problem.

Lee F.

[lckiii]

Does anyone have any experience using old computer power supplies to power their trains.  They seem a lot cheaper alternative to several ZW's; realize that you woudl have to wire them through a rheostat