DCC track power question

[mrredrunner100]

Can you use a computer psu (power supply unit) to power a DCC layout? We have a lot lying around and just wanted to know if you can use them for track power in a select controller

 

Thanks

Mrredrunner100

[poliss]

Depends on exactly what the output from the power supply is.

[Fishmanoz]

The important things are that the PSU has the same output voltage as the correct power pack, can supply at least one amp at that voltage and has the right connector with the correct DC polarity as per the standard supply.

 

And if you mean the internal

 

supply that powers a desktop PC, you will need to know exactly what you are doing to find the correct output that has the right volts, ensure all the other outlets have been properly dealt with so they can't accidentally touch something. In fact, for this

 

type of supply, if you are asking the question, the chances are you shouldn't be trying it. If you are talking about a laptop supply that has the correct volts and plug, that's another matter and would work.

[Fishmanoz]

And remember, if you try it and whether it works or not, you will almost certainly have voided your warranty on the controller.

[Fishmanoz]

And remember, if you try it and whether it works or not, you will almost certainly have voided your warranty on the controller.

[Fishmanoz]

Sorry about the repeat post, the site is being slow responding and tricked me it wasn't responding at all.

[poliss]

With my controller I emailed the manufacturer with the specifications of the power supply I intended to use to ask if it would be ok.

[Gregd99]

I just had a look at the spec for a 450W PC PSU. The +12VDC rail, which might perhaps be useful for DCC, was rated at 33 Amps.

 

A 550W unit could supply 41A.

 

As an engineer, I would suggest that unless you are very familiar with switch mode

 

PSUs and appropriate protection it would be prudent to be very cautious about using a supply that can supply that sort of current.

 

 

[poliss]

An internal PC desktop power supply would definitely not be suitable for a DCC controller.

Even a 10 amp power supply can melt the wheels on a 00 gauge loco.

[AlexPW]

Another issue would be the imposed DCC control signal onto the power supply rails,it may supress the control signals getting to the loco's.... bad news all roundif things go wrong in my book.

[poliss]

That's not how DCC works Alex. DCC isn't a signal. DCC is variable frequency alternating current. For a much simplified explanation,with some errors (there's no such thing as bi-polar DC. That's just AC). see http://www.awrr.com/dccintro1.html

The

 

power supply to the controller can be AC or DC depending on the model of controller and that it has a full wave rectifier inside.

[mrredrunner100]

Hi

Thanks for the replys, I don't think I will try it sounds quite risky, I thought it might be another way rather than buying the hornby power supply. You said about an external power supply (like a laptop one) and if it had the right connection and

 

gave out about 4 amps would that work

 

Thanks

Mrredrunner100

[Flashbang]

Hi

A replacement power supply for the Hornby DCC consoles must have the following criteria...

 

1) Its output must be 15 volts dc. Not ac.

2) Its output current should be no greater that 4.0Amp.

3) Its dc moulded connection plug must be of

 

the same size as used by Hornby.

4) The moulded plugs polarity must be the same as required by the DCC consoles socket. i.e. the central tube of the dc plug is positive or the outside rim is positive. Which is correct. Only looking at the existing old PSU

 

label will reveal this.

 

If you're able to find a PSU which meets 1 to 4 above exactly, then all is ok otherwise don't use it.

Its probably far cheaper and easier to obtain a new Hornby 4.0Amp PSU P9300.

[Graskie]

You've thrown me a bit, FB. Don't you mean AC, not DC in 1)for DCC output?

[Rog RJ]

Flashbang is correct.

 

The Elite and the Select both require a 15 Volt dc (direct current) power supply.

[Graskie]

Yes, thanks for that. I didn't realise the supply to my Elite was DC. I've just checked the bottom of my power unit and that confirms DC output. So, presumably the Elite itself changes that DC supply to AC for running purposes, with an auxiliary uncontrolled

 

DC output as well, of course.

[AlexPW]

Post a new reply...

[Fishmanoz]

Yes Graskie, the Select, Elite and eLink all generate the DCC output using the DC supply volts. This is the usual way many electronic circuits work, starting with a DC supply, then generating the required output from it. Even when connected to AC mains

 

power, the first thing that happens is that power is converted to DC for use in the electronics.

[Fishmanoz]

Even decoders use a bridge rectifier and capacitor to convert the DCC to DC to run the logic circuits in the decoder.

[Blackbird]

Any 12V DC supply can be used to power a basic 12V DC model railway, (PC PSU or 12v battery charger), however certain precautions must be taken. A PC PSU has a regulated output of 12V DC, whereas DCC systems run at 16-18V. So may not be adequate on volts

 

drop to a large system. With reference to current supply, they have a much higher current capacity (short circuit rating) so fault current limiting (protection) must be employed, i.e. a suitable fuse or MCB (suggest 6A) in the DC supply.