Function only decoder

[Forum-1211528]

Hi,

Can anyone let me know the easiest way to use a Function only decoder (to turn on/off street and house lights) using Railmaster.

Thanks

[Howbi]

Hi Ukbish...............the max power capabilities of function decoders is limited and probably is not the best route to powering lighting, eg 5 LEDs at 20ma = 100ma which is max on some decoders per function........using RM and the Hornby R8247 accessory decoder you can control a relay(s) to switch your lighting and have a much greater amperage at your disposal.........HB

[Chrissaf]

I agree with HB entirely. Using a function output for general layout lighting is totally unsuitable. By all means, use the function output to switch a relay to turn on the layout lighting (via a dedicated layout lighting supply - see below). But do not connect the function output directly to the lighting. Layout lighting even when using LEDs can easily and quickly add up to some significant current. I have just upgraded my friends layout lighting power supply from a 2 amp one to a 6 amp one as he was getting close to the limit of his 2 amp one & his layout is only 8ft  x 6ft.

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This leads on to another recommendation. Why waste valuable DCC current (see current usage comment above) on general layout lighting that can be best reserved for running locos. Use a separate dedicated power supply for layout lighting, not only that, but you want to keep your DCC supply as electrically 'clean' as possible if you want to avoid DCC loco control problems. Using your DCC power to run layout lights (lots of additional wires running all over the place under the baseboard) increases the risk of picking up induced interference into the DCC signal.

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A function only decoder is likely to actually cost more than a normal R8249 loco one with auxiliary function outputs. This is no different to Hornby's recommendation to use a R8249 decoder to modify their Turntable for DCC operation. The same principle applies, only this time you use the function output rather than the motor control output.

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In answer to your question about controlling it in RailMaster. And assuming that the function output switches a relay as per the recommendations above. 

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Treat it as you would a loco. Create a dummy loco in RM, and use one of the normal loco function buttons to switch the relay.

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Or use HB's suggestion to use a port on an Accessory Decoder to switch a relay. This saves creating a dummy loco, as the lighting will just become an Accessory Decoder address, just like throwing a point motor. Note: the Accessory Decoder port would need to be configured for always on (if using a standard relay) or pulse (if using a dual coil latching relay - do not use a single coil latching relay as that won't work).

[Forum-1211528]

Thanks for your replies. I think I will keep it simple and use a separate power supply with an on/off switch then.

[96RAF]

I used the controlled output from an old anlogue controller, which allowed me to vary the brightness of my layout lighting to suit the mood.

[mjb1961]

Hi ,,,,I use a 12v power supply that my wife had for lighting in one of her dolls houses which will power at least 50 bulbs ,and because I find them a little too bright I run them via a 12v dimmer switch ,£1.64 from China ,found on eBay ,,,you can use the same power supply for all your auxiliary lighting ,I E ,,zebra crossing flashing beacons ,street lights etc ,,,,,,best to keep it simple ,,,,,,mjb