What is the best source for a 12 volt DC power supply? Would a HO transformer work? It will be used to run small DC motors for animations. I believe the HO transformer would also give me a reverse option .
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A cheap HO powerpack would do the trick just fine, as you say, an easy reverse option as well.
Just add an appropriate bridge rectifier to any AC transformer. You can get a 25 amp one at Radio Shack for about $3. Hook the AC taps to the 2 terminals marked ~. Use the + and - out for your accessories. If you add a capacitor you will increase voltage 41%.
Dale H
Buy an MTH Commander. DC out, or DCS, and passes DCC. It's powered by the normal Z1000 brick, a nice unit, inexpensive, with digital voltage and amps displayed, inbuilt circuit breaker too.
WOW! You're recommending he buy a whole control system for a $5 power supply? 
Radio Shack sells wall warts that are just fine but the cheapest way is all those 12v 'chargers' that end up in a draw somewhere after the little gadget they came with is no longer in use or has been upgraded.
Joe
In the CB world during Trucking we had a number of devices that did nothing except feed clean 12 volts to transmit and receive on. They should still be dirt cheap at any number of sources.
In the old days we just connected them to whatever two wires we find to the batteries. Sometimes they burned the insulation off, turned red hot and set fire to the cab. No worries. Just slap on some leather gloves and yank em.
Digitrax makes some pretty durn good regulators that provide up to 20 amps of power in 12 volts.
My favorite source for 12 volt power is off Newegg dot com. They sell mountains of computer power supplies that are extremely precise. You might want to spend a few dollars more and put a Active UPS battery on there too. Utility power is quite dirty.
Modern PC power supplies can supply a ton of power at 12 volts, and the regulation is quite good. They can also be pretty cheap.
I can't really see the expense of a UPS, I'm guessing if power goes out, the rest of the layout will be dark anyway. 
I agree with grj on the converted PC power supplies.
They are cheap and easy to come by.
Most have several outputs including 12 VDC and 5 VDC.
The latter works well for Miller signs, and the 12 VDC has many uses around the layout.
Rod
Would the PC power supply be something for a laptop or desk top? Would BEST BUY have these? I have an HO transformer trainpack model 100 that I use to power my Bowser turntable. It always shuttered while rotating. I always thought that it was mechanically sticking. After reading these replys I am wondering if the turntable is underpowered vs mechanicaly sticking? I was going to spend money to replace the turntable$$$ This may be a much cheeper option. I did try this small power pack and it seemed to rotatate the 1RPM Hankscraft motor sufficiently.
I'd order it on-line from a place like NewEgg, you'll get better prices and a better selection. Here's a typical example: Antec VP-450 450W ATX 12V v2.3 Power Supply
This supply has two 12VDC outputs, each supplying up to 18 amps, should be enough for a whole layout.
Go to amazon.com and do a search for "12 vdc supplies" - you'll be surprised how many come up at prices starting under $3. Then do a search for "led power supplies" and more will come up. I have bought several of different amperage ratings, and all have worked fine.
Good luck,
Alex
The good thing about PC supplies is the output wattage, it's in the 100's of watts for even the most inexpensive ones.
I purchased a Antec VP-450 DC power supply from New Egg. It comes with multiple connectors? 20 pin, 4+4 pin 6 pin ,floppy connector etc. Which wires do I use to get my hot and common to feed a terminal block?
First off, you'll need a "start" switch to turn the supply on.
Here's an ATX 24 Pin P/S Pinout Diagram, you can see that pins 15 & 16 are shorted to turn on the supply.
You can also see here the connections for the various voltages. Note that you should have a 2A or more load on the 12V output for the supply to work properly.
The Yellow leads on the various other connectors are 12V, and the red leads are 5V, obviously the black ones are ground.
Go to the manufacturers' web site: www.antec.com Click on support, then navigate to the product manuals. download the VP-450 manual.
I'm guessing you didn't download the manual. It doesn't tell you anything about how to use it outside the PC environment, it's a plug it here manual, no technical details.
yep, john. manuals are hit & miss-- sometimes they are good, sometimes not. this is one of the nots. your link is real good, mine isn't.
It's great if you want to plug it into a PC.
I've pressed a number of these into service for folks, so I know exactly what it takes to make them work in a non-PC environment.
I usually mount the switch and a terminal block right on the case, makes a handy power supply with lots of OMPH.
amtrack5800,
I recommend Signal Transformer's # 241-8-12. I use over a dozen on my layouts and over 20 years never had a failure. Commercial quality. Cant say the same for Radioschack.
Les Lewis
Originally Posted by New Haven Trolleys/ NH RR:
amtrack5800,
I recommend Signal Transformer's # 241-8-12. I use over a dozen on my layouts and over 20 years never had a failure. Commercial quality
They're over #30 at Digikey, that's a bit expensive for a 100VA open frame transformer. You'd want that in some sort of enclosure since the AC terminals are exposed. Any similar design transformer will probably outlast the owner, and there are some that can be had for a lot less.
John, Thanks for the reply. Based on your diagram I can use pin # 10 to power my
# 1 terminal block and pin # 11 for a second terminal block. I can use pin 3, 5, 7, 15, 17, 18, 19,or 24 for the ground. The connector is actually a 20 + 4 pin motherboard connector. The # 10 pin is part of the 20 pin motherboard connector and the # 11 pin is part of the 4 pin motherboard connector.
What is the 4+4 ATX12V, EPS connector. It says that it is part of the 12V2 Rail?
There are two 12V rails, it appears that the MB connections you mention are supplied from the second 12V rail, the rest of the 12V outputs come from the first 12V rail.
This indicates if you're going to use a lot of 12V power, you should probably consider splitting the demand between the two rails.
Note that the total power available is 450W maximum. If you add up all the maximum ratings of the various outputs, you'll come up with more than 450 watts. Obviously, you can't run all the outputs at maximum, something to keep in mind. If you managed to max out the 12 volt outputs, you'd be pretty much at capacity.
12V @ 36A total = 432W
Info on using a pc power supply for accessories:
http://www.jcstudiosinc.com/BlogShowThread?id=222&categoryId=
http://www.wikihow.com/Convert...o-a-Lab-Power-Supply
The J&C Studios O Gauge Archive is a gold mine of information.
Pete
One thing that's not mentioned is some accessories want to run on AC, a number of PW Lionel ones come to mind. Also, the polarity may be an issue, in the Intermodal crane they use DC motors and diodes, but connecting the polarity backwards will probably result in no operation.
+1 for computer power supplies, but look around and buy used! Most any local yard sale around here has old computer equipment for dirt cheap. Buy up a few old computer towers cheap, harvest the power supplies, and heave the rest. You usually get +12, +5 and -5, well regulated and plenty of amps.
Regards,
I too have had good luck with a PC power supply. Inexpensive, and great regulations. The wall warts do not always work on certain circuits due to the ripple in the supply.
The one I got has four isolated 12 VDC outputs, with more than enough power for everything I do on my layout.
