After installing decoders in 2 Trainmasters and a B23, what do I do with the light boards that were replaced? Are they sell-able? [ 06. January 2005, 20:53: Message edited by: nscale_lover ]
Mike Well I have never tried to sell any so I have a box full of them. Unitl the whole LED thing was worked out I was cutting the white LED's off and soldering them to the decoders, but not any longer. So now they are just collecting dust. Steve
I use the light board to light up buildings. I especially like the yellowish lights. Gives a very good incondescent lighted look to the buildings. David
LEDs are fairly simple, fairly robust little things. You could probably google for more details, but a rough rule of thumb is one LED needs 1.5V (red), 1.8V (green/yellow), 3V+ (blue) or 4V+ (white?) and 15-25mA to glow. Too many amps can burn them out. Hence LEDs almost always have a "current limiting resistor" fitted. (Power_Supply_Voltage - LED_Voltage)/LED_Current = approximate resistor value required. So for a yellow LED on a 12V supply with 20mA current desired, (12-1.8)/0.02 = 10.2 / 0.02 = 510 ohms. Nearest standard value resistor is probably 560R, which gives you a little less current and hopefully lengthens the life of the LED. So, the short answer is, with the correct Resistor fitted, any power supply can be used. Hopefully the Resistors already on a light board are "correct" for 12V operations.
The light boards I have used have diodes/resistors onboard the light board that drop the voltage. I just connect them to a 12 VDC buss that I have running around my layout. You could also just remove the LEDs from the board and wire a 1k ohms resistor in series. David
