DCC Street Lights

[David55]

I am looking to add street and station lights to my layout. Can these be run through a accessory decoder?

 

I have read other posts on this site but am not sure how many I can run.

[walkingthedog]

I would have thought a simple power supply through a switch would be sufficient, after all they will be either on or off.

[Flashbang]

Hi

The answer is yes they can, but..... You will need a DCC system that can write CVs to allow the accessory decoder output to be set to continuous - The Select cannot do this.

Secondly, why use the DCC power to feed lights? Keep the DCC for running

 

the trains and do as suggested and use a small 'Wallwart' (plug in type) 12 volt dc power supply and feed the lights from that.

[David55]

Thanks both for that.

 

I will be splitting my layout into four area's each will have it's own switch.

 

I expect to have around 15 lights per area.

 

Two questions:

 

1. Will one unit power them all or do I need a power unit for each.

 

2.

 

When doing the wiring, is this done in tandem.

 

Hi

The answer is yes they can, but..... You will need a DCC system that can write CVs to allow the accessory decoder output to be set to continuous - The Select cannot do this.

Secondly, why use

 

the DCC power to feed lights? Keep the DCC for running the trains and do as suggested and use a small 'Wallwart' (plug in type) 12 volt dc power supply and feed the lights from that.[/reply]

[Fishmanoz]

The answer to both of your questions is that it depends. The first thing to determine is if you are using LED lights or not? LEDs use far less power and will certainly not overload a single power pack. And depending on the pack, incandescents in those

 

numbers are unlikely to either.

Assuming you are using that single pack, you now wire each of the 4 areas in parallel and put a switch in series in each so they can be turned on and off independently. Then wire all the lights in each area in parallel (and

 

in series with the switch). Except for LEDs, you could use a series parallel combination - say 3 lots in parallel each of 5 LEDs in series. This is because the LEDs don't need the full 12 or so volts from your supply where the incandescents do. To learn more

 

about LEDs, particularly if what I've said is confusing, do a forum search on LED and you'll find heaps on both types of lamp, how much current they draw, what voltage they need and the use of series dropper resistors when wiring LEDs to 12V.

Hope that

 

helps rather than confuses but a little simple electronics knowledge is needed to wire lamps correctly.

[Fishmanoz]

If you still want to control them by DCC, you would connect each area to a separate decoder port so you can switch them independently. And again, you have to write the decoder CV on each port for continuous as described in the earlier post.

[Fishmanoz]

A good site to find out more is Brisn Lambert at http://www.brian-lambert.co.uk/Electrical-2.htm#Signals%20&%20Lighting....

[David55]

Thanks for all your replies.

 

I have a Hornby P9000W AC Adaptor, can this be used for supply?

 

Fishmanoz said:

 

A good site to find out more is Brisn Lambert at http://www.brian-lambert.co.uk/Electrical-2.htm#Signals%20&%20Lighting....[/reply]

[Flashbang]

Hi

Firstly the Hornby P9000W has a maximum output of 19 volts dc at 0.5 Amp (1/2Amp).

 

Next you need to determine whether your lights are filament lamps or LEDs?

 

If LEDs you must fit series resistors to each LED lamp. On a 19 volt

 

supply I would be looking at using minimum 1K8 or 2K2 at 1/4 watt or a larger wattage resistors, one per lamp

 

If filament lamps are used then you really need to know what each lamps current (Power) consumption is. Then times that by the number of lamps

 

lit. I always assume worse case and take 0.075A (75milliamp) as around the normal current demand of one 12 volt filament lamp. So 15 times 0.075 is (15*0.075=1.125) or 1.125Amp. Which EXCEEDS your Power supply and will cause its overload cut out device to

 

operate.

Four times that which is what you stated (4 x 15 lamps) the loading for filament lamps would require a PSU that has a rating of at least 4.5Amp!

 

If LEDs then I would assume each LED consumes a maximum current of 20 milliamp on the supply

 

with a series resistor value as mentioned above. So your 60 lit LEDs would then require a PSU current of 1.2Amp (60 x 0.02 = 1.2) Again your P9000W is unable to deliver this as its maximum is 500milliamp (0.5Amp) or 1/2 Amp!

 

If you really want to power

 

60 lights regardless of their type, then get a PSU that is capable of delivering the required current, plus a safety margin above that maximum too. Look for a PSU that can supply ideally 12 volts dc at 2.0Amp for LEDs and 12 volt dc at 5 Amp for filament lamps.

 

ebay is often a good place. BTW 5 Amp is a huge current demand and your wiring must be able to carry this current easily. I would split the circuits as you suggest into for LEDs two and filament lamps into four or even five and have each protected by

 

its own 1.0Amp self resetting overload circuit breaker, as sold by Maplin for example Part No AK07H.

[Flashbang]

Just to add... 19 volts is far too high for most grain of wheat or grain of rice filament lamps as they are normally rated to a maximum of 12 volts. Though I guess the P9000W output will fall rapidly under load to less than 19 volts?

You could of course

 

add a series resistor to filament lamps but they would need to be a higher wattage (1Watt or higher) rated type while their OHM age would have to be calculated once the wattage or current of each lamp is known.

[Fishmanoz]

Well laid out Flashbang, I was hoping not to have to do that calculation.

 

With the high 19V supply, you could run series parallel combinations, filaments in series pairs to have them under their voltage rating and LEDs in say 5 in series with a

 

limiting resistor.

 

But the clear message is that lots of of lights use lots of power and proper calculations need to be done, then appropriate wiring and circuit protection used to keep everything safe.

 

And it's obvious that LEDs are a far

 

better proposition than filaments. Even your house lights are going to be replaced by affordable LED lights very soon, helping save the planet with reduced emissions as one of the benefits.

[David55]

Thanks for your reply.

Having looked on the internet, there is a 10amp unit supplying 12 volts.

Since not everything is available in LED form and that I may fit more than 15 in some area's I think this should be ample.

There

are also several sites selling lights that come with resistors, so I think that is the route I'll take.

Thanks for your help again.

Flashbang said:

Just to add... 19 volts is far too high for most grain of wheat or grain of rice filament

lamps as they are normally rated to a maximum of 12 volts. Though I guess the P9000W output will fall rapidly under load to less than 19 volts?
You could of course add a series resistor to filament lamps but they would need to be a higher wattage (1Watt

or higher) rated type while their OHM age would have to be calculated once the wattage or current of each lamp is known.