Just finished installing the LED strip lights in
three of my HO passenger cars. Wow,
Works great...not a flicker anywhere on
the layout. As expected the
capacitor in the circuit keeps 'em on.
But my addled brain is totally confused.
With the car taking power from the DCC (Bachmann EZ)
track, I measure 16.95 Volts DC across the capacitor
after the bridge rectifier with the LEDs burning.
I was anticipating a lower
voltage. Anyway...to get the desired low brightness level
it was necessary to use 1410 ohms of resistance between
the cap and the LED strip. That results in 8.6 Volts DC
across the LED input terminals when they are burning.
That's a voltage drop of 8.35.
Using the rule, 1 volt drop for each 50 ohm resistance,
I should achieve 8.35 with one 470 ohm resistor. 50 X 8.35 = 417.5.
So why did it take 3-470s in series (1410 ohms) to get to 8.6 v?
Is the LED 'load' so light as to not get the full voltage drop
from the resistors?
Ain't it fun the work on trains? Helps to start out addled.
If you're dropping 8.35 volts across 1410 ohms, you're only drawing about 6 milli-amps to light the LED's. That's obviously fine, but you mention "the brightness desired", apparently you didn't need the full brightness of the LED's for the application.
Gotta thank you both for guiding me on this car lighting
I didn't like the extremely bright effect of the strip LEDs
at full 12 volts...So started adding 470's in series until
I got what I wanted with 3 of 'em. Looks like the
old florescent tubes that were used in these old Silver Side
Do have a problem with the Intermountain metal 36" wheels
used for power pickup...they are excellent quality BUT the
flange is much finer than normal wheels...these cars have
talgo trucks and that seems to pull the wheels off the track.
Gotta go back to the regular metal wheels...pshaw. Never
had a problem with their old plastic wheels with the deeper
I plan to light up some cabooses next...will want them to
be substantially dimmer still.
Main headache...can't figure out how to take the shell of
the frame on any of the various Cabooses
I have found that if the car is too light adding weights over the trucks will really help out keeping it on track.
Intermountain make 2 sets of wheels, .110 and semiscale wheels
Semi scale wheels do have much smaller flanges than the .110 wheels.
Tell me which ones you have and I'll get you the right ones.