Model Railway Forum

A question about dc power supplies.
I have built my own controllers (3) for use on a 3 track non doc system.
Will a 12 volt supply rated at 360watt / 30 amp be sufficient

Mod Note 1 : Moved into own topic for clarity.

Mod Note 2 : Using self built controllers is NOT recommended, due to the safety concerns of mixing 240V and 12V electrics.

Mod Note 3 : 30Amp is FAR above what you'd ever need for a railway. Even though the voltage is low, it's still a dangerous amount of energy to be playing with. Remember, the Volts Jolt, but the 'Mils Kill!

Yeah... that's probably about 10 times the capacity you need.

Most locos draw much less than 1 Amp, so if you are looking at 3 trains in service, 3 Amp would be fine, 5 Amp would be overkill.

In 00 scale you only need about 1amp (and usually less) per running loco so your power supply seems to be rather over specified.

Snap!

@BobH

Would I be correct that your power supply is a ex PC ATX unit?

Regards,

Steve D.

Thanks for the prompt response guys.
What I have built are the circuit controllers ( rheostat and reversing switch.
I intend to purchase the power supply separately and mount it off board. The circuit controllers would then be connected to the power supply via suitable wiring

Stese wrote: ↑Wed Nov 13, 2024 2:46 pm @BobH

Would I be correct that your power supply is a ex PC ATX unit?

Regards,

Steve D.

Hi Steve power supply not purchased yet just seeking advice as to how to proceed

Avoid such a large output power source. 30Amps at 12volts is 360 Watts. Think how hot a 60watt light bulb gets. A short circuit on that power supply can result in a fire due to wiring melting. A 3.0Amp 12 volt regulated power supply should be ample. Example https://www.amazon.co.uk/12V-3A-Power-S ... d_source=1

Factory made DC train controllers have overload trips set to around 1.25 to 1.5Amps for N and OO locos, while O gauge and larger may well have slightly higher rating overload trips of 2.0 to 2.5Amp.

Rheostat controllers are very old fashioned today. Power transistors are the way to go IMO. Ratings of 15 Amps loading are normal for many power transistors.

BobH wrote: ↑Wed Nov 13, 2024 3:31 pm Hi Steve power supply not purchased yet just seeking advice as to how to proceed

I'd suggest a PSU such as the one Brian has linked.

The thought of making my own controllers would terrify me.
I use Gaugemaster ones on my layouts, including one that's decades old, inherited from my dad.