Model Railway Forum

I have been told I need a 12volt regulated supply will this be ac or dc please

I would say DC

I have never heard of a regulated AC supply, yes DC out of an AC/DC transformer can be regulated.

A regulated supply is dc.

You haven't mentioned what you need the PSU (Power Supply Unit) for? As others have said a Regulated supply is DC. However, its current output is also important as they vary considerably.

Lets say you want to power layout lighting - buildings, lampposts etc... Filament lamps fitted with Grain of Wheat or Grain of Rice lamps frequently will consume around 70 milliamps (0.07A) each at 12 volts. If you have ten all lit at once then you're drawing 700 milliamp (O.7A) from the supply. So a minimum 1.0 Amp (1000 ma) power supply is needed to allow some leeway and better and ideally obtain one that has an even higher amperage of say 2.0Amp (2000 ma).
LED illumination draws much less current typically 10 milliamp per lit LED or less, but still opt for a larger power supply than needed, it wont hurt at all so long as its not too higher current i.e. 5 plus Amps when smaller sub circuits then are taken off the main supply and these need individual fusing or circuit breakers fitted.

A typical example is here of a 12v DC regulated power supply The 2Amp (24watt) version being ideal for most model railway lighting use...Link to PSU It aso comes with a connector which is very handy for easy wiring beyond the PSU.

great stuff thanks for the advice its for a mega point controller board

More information is really needed...

Mega points controller - Solenoid or servo motors?

If Solenoids, you will need a AC 16-18 volt AC power source at 2.0Amp to feed and operate the board and solenoids.
Plus a regulated 2.0Amp 12volt DC power Supply for the panel processor unit.

For Servo board power you will need a 12 volt DC regulated power supply of at least 2.0Amp.

So not quite as simple as initially asked or perhaps as cheap as thought!