I happened to have some 12 v LED's that I used in the front and back of my Rivarossi Big Boy and Challenger locos. They work great and I didn't have to use any resistors. Is there a reason you don't hear about them on the forum? I found they look great and just like the 1.5 volt ones in my other locos (with resistors of course).
This photo is of the headlight on the Challenger.
- Bob
Life is what happens while you are making other plans!
Bob,
I am no expert but I understand there is really no such thing as a 12v LED. These are undoubtedly actually LED's that work on 3+/- volts with built in resistors. But as you found out, they work for some things in the model railroading world.
Yup, no such thing as a 12V LED or a 5V LED - they are just regular LEDs with the resistor built in. You cna also buy blinking LEDs as well - they are regualr LEDs with the blinking circuit built in.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Well, I guess my question now is; why don't more modellers use them? If the resistor is built in and you don't need to solder resistors in line with the LED and they are the same size (mine are 3mm) wouldn't you expect to see them in use more? I am all for less soldering of components in a locomotive.
Not often found in the proper white color for use as headlights in the main reason. And often the voltage at the function outputs of a decoder are over 12 volts.
rrinker Not often found in the proper white color for use as headlights in the main reason. And often the voltage at the function outputs of a decoder are over 12 volts. --Randy
You could add a zener diode. But then you're back to adding an extra component and might as well use the resistor :-)
John
The reason you here very little about them should be obvious. The LED's ready for 12 volts are relatively new for model railroad use.
Single LED's with no resistor have been around for many years. I started using them around 1972.
Since 1996 I have used LED lamps in industrial machine controls that work on 120 VAC power.
Things are continually evolving. Someone has to develop the LED's with resistors and different lighting characteristics that are suitable for model railroading. Different colors will require different resistance values. I have seen that with bi-polar red/green LED's Different intensity using the same value resistor.
Surface mount LED's with a resistor and suitable lighting characteristics is another issue. Some designs will not please all. There are many variables in LED lighting, not just headlights. Some rivet counters count all the rivets and are very demanding on what they want.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Thanks for all your comments and info. The ones I am using were on Ebay and are 3mm warm white, which is just what I wanted for my HO headlight and backup lights. I just thought they were perfect for HO logos, buy that is just my preference. If I have any problems with them like over voltage from a decoder, then I will go back to the external resistors.
Most 12 volt LED's can be operated safely to at least 14 volts. If you add the ~1.5 volt drop of the decoders bridge rectifier, that allows for a track voltage of 15.5, so as long as you kepp the track voltage 15.5 volts you shouldn't have a problem with overvoltage.