Replacing bulbs with LED

H

Hekate

Registered
Another problem I have is the standard incandescent bulbs fitted to my Locos seem to last about 10 minutes. Can I replace with LEDs ? if so what type and value of resistor. I have a combination of digital and analogue locos.
 
Are you using the wrong voltage bulbs? Should be lasting more than "10 minutes"!

Resistor value depends on what voltage is being supplied, the forward voltage and the current requirements of the LED.

There are online resistor calculators such as http://led.linear1.org/1led.wiz

So, as a basic example if the voltage is 5V, the LED has a forward voltage of 2V and requires 15mA current, the calculator reckons a 220R resistor. If the supply voltage is 18V this goes up to 1.2K resistor, and at 24V you'd need a 1.5K resistor.

The forward voltage and current varies for different colours and sizes of LED.
 
In my opinion many modern white LEDs look unrealistically bright.especially on steam locos. Higher value resistors help, with my last installation I used a 3300 ohm resistor for each bright warm white led as I had plenty spare. I'm very happy with the result.
 
Whatever the voltage, I would suggest you start with a 1K resistor.. As Neil says, they are very bright, which just doesn't look right.
 
1K suits most uses with out any calculations.
 
Rather out of my league but I use yellow LEDs as they look more 'right', if I was going to model a modern industrial building then I would use white LEDs to look like flourescent tube lighting.
 
I use a Massoth 1200z and all locos are chipped, so therefore lights are 5V
thanks
Thanks for all the helpful replies, I guess I just order LEDs from Maplin or similar.
 
Hekate said:
I use a Massoth 1200z and all locos are chipped, so therefore lights are 5V
thanks
Thanks for all the helpful replies, I guess I just order LEDs from Maplin or similar.
Click to expand...

Not necessarily. Could be why your bulbs are not lasting. More recent offerings from the likes of LGB do have circuitry for 5V lights, However, older models use full track voltage, 18 or 24V
Other makes may well use full track voltage.
Using the Massoth will not automatically set light voltage at 5V
What locos are blowing their bulbs?
 
There's the key... Hekate's reply says "because I use DCC, there is 5 volts to the bulbs"

So you told use the command station, but not the important part, what decoder?

Also, did you reference your lights to the common (blue) wire or to something else?

And you did not answer the question about the track voltage.

Can't help you much without knowing any of the environment.

Greg
 
Also depends whether the lights are connected directly to the decoder or via the loco's main board (and any voltage regulation).
Most decoders default to driving function outputs at full voltage (ie. near track voltage) unless programmed to do otherwise.

As Stockers has pointed out, you can't assume the lights are being driven at 5V unless you're sure of the decoder settings and the other circuitry involved.
 
If you decide to go for LEDs then check the Massoth site as they are now showing ready-wired LED kits to replace head and rear lights. The kits can cope with voltages between 5v and 22v so no decoder changes are needed (apparently).
 
There are screw E5,5 led bulbs available in different colours including warm white.
These bulbs are not polarity sensitive and already have resistors in their base. Depending on which ones you go for, they can go up to 19v (I have tested them at 22v and they are perfectly fine).
These ones will light at 7v (if using DC) but if using DCC you can set what voltage you wish to feed them.
They are a direct replacement for any E5.5 sized bulb.
They are also available i the larger E10 size which is used in some older LGB locos
Yes they are more expensive than wiring up your own LEDs but factor in the time taken to replace the bulb holder etc and the cost becomes more attractive.

http://www.ebay.co.uk/itm/10x-LED-1...961234?hash=item2a1828eb12:g:hwYAAOSwpDdU5GmJ
 
I have never seen an LGB engine that outputed 5 volts to lights or smoke unit!!!!

I usually see 6.2 to 6.8 volts on these.
When calculating resistors for leds I take an easier approach as follows:"
For 10ma leds, you need 100 ohms per volt dropped. So a 3 volt led on a 12 volt supply needs 9 times 100 ohms for 900 ohms and the resistor would be 910 ohms.
For 20ma leds you need 50 ohms per volt dropped. (or use a CL2N).
 
Dan said:
I have never seen an LGB engine that outputed 5 volts to lights or smoke unit!!!!

I usually see 6.2 to 6.8 volts on these.
When calculating resistors for leds I take an easier approach as follows:"
For 10ma leds, you need 100 ohms per volt dropped. So a 3 volt led on a 12 volt supply needs 9 times 100 ohms for 900 ohms and the resistor would be 910 ohms.
For 20ma leds you need 50 ohms per volt dropped. (or use a CL2N).
Click to expand...

Ok, I'll bite..

? CL2N ??
 
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