N gauge yard lamps for diesel depot

[locofan]

Hi all,

 

I've purchased some n gauge yard lamps with resistors but they came with no instructions. I believe they are 12v lamps. I also believe DCC is 16v. I have been told I can connect them straight to the DCC power bus. Surely they would blow if they were connected? Also is it possible one of you folks could show me a wiring diagram? Any help much appreciated.

[Only-Me]

most if not all model lamps be they led or filament lamps are DC.

 

DCC is AC, if you connect them they won't work/may blow up... I would suggest 9 VDC is a good volatge for lamps.  My layout is fully DCC, however I have a 9V DC bus (maplins dc adaptor about £7) which powers all the lights / leds etc... It doesnt matter which leg you put the resistor on, just make sure the voltage is DC and 12V or below.

[locofan]

most if not all model lamps be they led or filament lamps are DC.

 

DCC is AC, if you connect them they won't work/may blow up... I would suggest 9 VDC is a good volatge for lamps.  My layout is fully DCC, however I have a 9V DC bus (maplins dc adaptor about £7) which powers all the lights / leds etc... It doesnt matter which leg you put the resistor on, just make sure the voltage is DC and 12V or below.

I have all six lamps in situ but not yet wired up. Each lamp has a resistor supplied with them. I suspect I'll need on/off switch. I have a gaugemaster analogue controller with a 12v output. I'm a little unsure of how to wire them all up so I can switch them all on/off with just one switch. Advice and/or diagram would be much appreciated.

[Phil S]

Some additional information on the lamps you have purchased woud be useful, if not essential to provide an accurate answer !

 

What instructions came with the lamps?

Are they designed to be connected in series - so that each sees only a part of the voltage supply?

Are they LEDs or filament lamps .... and if the latter, are they 'grain of wheat' or similar, or 'micro bulbs - a more modern variety which uses a lower voltage.

 

LEDs are a  non-linear, 'dc' device, in that they conduct only 1 way, and above a certain voltage, - but they can, and are used with ac supplies: HOWEVER  usually they would have a DIODE included, so that they actually only used one direction of the power supply.  

Some LEDs are destroyed by a reversed voltage of just 5V (and some special types, such as flashing LEDS, have ICs built in which are destroyed with just 0.5V reverse voltage, even though they may be designed to operate off a forward  12V!!)

 

Micro bulbs can be used on ac or dc without concern.

 

Model Railway Accessories were traditionally supplied to run off the 16Vac 'spare'/aux' output of a railway controller ... an increasingly rare output nowadays; BUT this meant that manufacturers would supply lamps with a suitable resistor and diode with which to safely run the LED(s) off AC OR DC.  (And note that a nominal 16Vac has a peak value of maybe >24Vdc especially when minimal current is being taken.) [Half-wave rectification, with a single diode, would then make 16Vac about the same power as 12Vdc.. but the apparent brightness might be different]

 

Modern Controller, in the EU, operate from more energy-efficient Switched Mode Power Supplies, instead of the old Mains-based transformers: and these usally have a well controlled DC output eg 15Vdc with the Hornby Select, which tehn gets further converted to the track dcc voltage.

 

Lighting can therefore be run from the track or accessory DCC bus - assuming sufficent power is available - and I use this as a 'visual diagnostic' to show that the track power is ON (eg Buffer Stop lamps).  However, if you have platform and street and building lighting, the current soon adds up, and a separate bus becomes a better choice.

IF you intend using '12V dc LED Lighting strip' then these really need to be powered cheaply and effectively from SMPS of 12.0V ... with maybe 3-4A output (check with a meter, or 20mA oer 50mm/3 LEDS).... in which case it would be sensible to standardise on 12Vdc for your lighting, and choose a resistor to place in series with the LED and protective diode (protecting against reverse connection).  My loft layout has about 3-4A @ 12.0Vdc for platform and lower-level lighting.