The capacitor probably absorbs reverse back emf spikes that would cause the LED in the opposite direction to flicker.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
Thank you everyone for your help
Tom
normally a capacitor used in this way would provide some power during brief losses in connectivity with track voltage. The bigger the capacitor, the longer the time. A typical LED draw ~10ma.
greg - Philadelphia & Reading / Reading
What is the purpose of the capacitor on this DC light board?
Then that part on the other side is definitely a capacitor. Looking at the traces, the part on the other side is directly across (parallel) with the LED. Definitely a capacitor.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
OK here is the backside with the resister. I looked up picts of SMT Cap and they look exactly the same as the one on the board. There are no markings whatsoever on the item on the board i have.
Thanks for everyones input
Get your Optivisor out and trace the circuit and an ohm meter. The meter should show you the device is a resistor.
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.
Can you post a picture of the other side of the board?
If that's from an N scale loco, then the two tabs on the right would be sandwiched in the frame, so that part, despite not looking like one, would have to be a resistor to keep the LED from blowing up as it would be connected directly to track power. A picture of the other side of the board will show if that device is wired in series or parallel with the LED.
An SMT cap...
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
By the color, I would guess a surface mount Tantalum capacitor but I would not expect to see that type of cap there. I think I see the positive terminal indicator mark on it. I cannot pick out the data even when I blow up the photo.
If it is a capacitor, you should see the value and voltage.
Diodes and resistors are usually a black body.
If you have a decoder laying around you can see the different color devices and info.
Google the info on the item. I have done that a number of times with surface mount items.
Can anyone tell me what the square device is that spans the 2 leads of the light on this light board. The board is from the front light of an Atlas RS3 N Scale eng DC mode.