Computer PSU for accessories and incidentals

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IanS
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Computer PSU for accessories and incidentals

#1

Post by IanS » Sat Oct 13, 2018 4:43 pm

Does anyone use a converted computer PSU for running their accessories (eg CDU/Points/Signals) or for other incidentals such as lighting up buildings/stations/streets or animation?

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Rog (RJ)
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Re: Computer PSU for accessories and incidentals

#2

Post by Rog (RJ) » Sat Oct 13, 2018 7:57 pm

I don't and I never would. IMHO they are far too powerful for model railway use and also potentially dangerous because they really should be enclosed, such as in a computer case, to prevent accidental contact with the components inside, such as could occur with scraps of wire or the bare ends of lengths of wire.

If you really must use one, have fuses as near as possible to the output wires and use an RCD (residual current device) or similar in the mains power feed to it.

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Re: Computer PSU for accessories and incidentals

#3

Post by Brian » Sat Oct 13, 2018 9:13 pm

100% agree with Rog (RJ) These PSUs are far to powerful for most model railway use. Many will be capable of providing 20 plus Amps. At 12 volts this is around 240 watts. Sufficient heat under loading to cause a decent fire!
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Re: Computer PSU for accessories and incidentals

#4

Post by Steve M » Sat Oct 13, 2018 10:36 pm

I said it many times on the old forum, I use a couple of 8amp cctv PSUs each split into eight 1amp feeds by using 1amp self resetting circuit breakers. Many such PSUs come with 8-way splitters that do most of the work for you.
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Re: Computer PSU for accessories and incidentals

#5

Post by AugustusCaesar » Thu Oct 25, 2018 4:30 pm

A few days old this thread but I have known folk use a PSU from an ordinary PC for accessories but obviously not for running trains themselves.
There are one or two modellors on YT doing exactly this. As long as your ampage and voltage is fine you are OK surely. Covering a PSU is simple... wooden or metal casing can make the whole thing safe enough. It depends upon how safe and conscious the user is when using these things but the two guys I knew a few years ago used these with no problem. Sadly neither are around now but before you think the worst they didn't pass because of dodgy wiring... :o
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Re: Computer PSU for accessories and incidentals

#6

Post by Brian » Thu Oct 25, 2018 4:53 pm

Sorry I have to disagree... As I've said before and in this topic too, these are best kept inside the computer. Users see them and think... Oh cheap power supply and 12 volts too! These devises have to be one of the most dangerous power sources in the uninitiated users hands!
Its all down to how powerful they are. Most can easily output 20.0Amps. At 12 volts this is 240watts of power. That's one heck of a lot! Most model railway wiring will burn out, possibly even catch fire under a fault condition at this rating! No one needs that amount of power for model railway use. :shock:

Users of these PSUs risk a Fire occurring, possible Electrocution if not installed properly in an suitable ventilated enclosure.
So why run the risk?

IMO far safer, if 12 volts DC is required, is to use a CCTV Power supply. These come in various current output ratings from around 0.5Amp to 5Amp or more. They are regulated too. Cost from about £4.00 upwards. Usually plug in or 'Brick' type and are totally safe as no additional casing is needed.

If any PSU is used with an output of over 1.5Amp then the output should, for model railway use, be sub divided into smaller current rated supplies, by splitting the output and passing each output via a self resetting 1.0Amp Circuit Breaker or fuse etc. This gives each sub feed local protection where the source is higher.
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Re: Computer PSU for accessories and incidentals

#7

Post by Chris » Thu Oct 25, 2018 4:59 pm

AugustusCaesar wrote:
Thu Oct 25, 2018 4:30 pm
A few days old this thread but I have known folk use a PSU from an ordinary PC for accessories but obviously not for running trains themselves.
There are one or two modellors on YT doing exactly this. As long as your ampage and voltage is fine you are OK surely. Covering a PSU is simple... wooden or metal casing can make the whole thing safe enough. It depends upon how safe and conscious the user is when using these things but the two guys I knew a few years ago used these with no problem. Sadly neither are around now but before you think the worst they didn't pass because of dodgy wiring... :o
I think you have nailed the issue squarely there when you say ' it depends on how safe and conscious the user is'

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Re: Computer PSU for accessories and incidentals

#8

Post by Stese » Thu Oct 25, 2018 6:12 pm

240W from a computer PSU is considered as small these days. Many PSU's run up to 750w, although the available current is often split between many 12v circuits... there are some PSU on the market that hit 1.2KW.

If you are going to use a computer PSU, cover it by all means but make 100% sure it has suitable ventilation otherwise it will overheat... at the kind of power available, if the PSU is in anyway faulty, you've got a dangerous fire in seconds.

As other posters have suggested, Use a small plug in type PSU, such as those for cctv. Plan your useage carefully so you know what current requirements, and give yourself a 10% margin for error. if you need than more than an amp or two, use multiple small PSUs.
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Re: Computer PSU for accessories and incidentals

#9

Post by mijj » Thu Oct 25, 2018 10:32 pm

I've a desk-top whose PSU went with a bang and a flash about six weeks ago, and that was it. It looks as if a capaciter close to the input side blew apart. It was a big bang and flash. It must have been a heavy current flowing. No more W7! I fitted a new PSU and I did identify that the mobo (mother board) was also gone. I did get one of those then sent it for repair. Well the CPU might also have gone :( .
Jim.

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