Power Supplies

I need some ideas for using various voltages on a HO layout. We've had a job going on at work where we're replacing hundreds of power
supplies in some modules sent in by a customer. These are mostly linear DC power supplies, though I think some models are switching supplies. We're replacing everything with new ones whether the old ones are bad or not. This means I have the chance to grab possibly dozens of good working power supplies for possible use on the future layout since the ones being removed will just be scrapped. The power supplies I have seen come in 5 volt, +-12 volt or +-15 volt (selectable), 24 volt, and 28 volt outputs. The 5 volt, 24 volt and 28 volt units come in sizes up to several amps, but the +-12 volt units are only 1 amp output. The only use I can see for 5 volts is building lights or some other form of animation, etc. The +-12 volt supplies can be used for turnout machines but I don't know how much a Tortoise or other stall motor draws, so I'm not sure how many could be powered from a 1 amp supply. I'm not sure of any use for the 24 volt or 28 volt power supplies. I think that's too high of voltage to use for an HO scale DCC booster power supply. Don't they require something in the 15-20 volt range? Any other ideas for using power supplies on a layout?
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Rick Jones
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Tortoise machines take very little power whilst stalled: about 16ma, so 30 or so can be powered by a single 9 - 12 volt 500ma wall wart (Tortoise instructions).
12V will make them run fast and noisy, and it is the MAXIMUM specified. I use 7.5volts on mine with two bi-polar LEDs (green for good, red for blocked path), and use the two DC power supply technique specified by Tortoise. They run quietly and at the right speed for me (about a second to throw).
You could use the 12v supplies to run 12 to 15 volt lights and other accessories.
Ed
in article snipped-for-privacy@corp.supernews.com, Rick Jones at snipped-for-privacy@extra.ev.net wrote on 11/5/05 4:06 PM:

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http://groups.yahoo.com/group/MRPics http://groups.yahoo.com/group/vintageHO
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I don't know if you can run a tortoise on 5 volts, but I think you can. If so, then there's your major use.
Froggy,
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Froggy @ thepond..com wrote:

Would a Tortoise or any of the other stall motor switch machines have sufficient torque using 5 volts to operate them?
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The switching supplies can be reprogrammed for lower voltages with little loss of current output if you find the right voltage sensing resistor. Linear supplies of that voltage rating will need to be derated for the power dissapated by the pass transistors although you can take another control circuit and hook it to the same transformer and get the full power of the transformer. Again, you need to find the voltage sensing resistors and change one of them. I will note that running a layout on pure DC isn't the best as there is no pulsations to make the motors turn easily at low voltages which means that you really want to build throttles that will do those things.
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Bob May wrote:

I plan to run my future layout on DCC. That's the biggest disappointment among the various voltages and current ratings that I may have a chance to pick up free - none appear to be the right rating for use as DCC booster power supplies.
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