Just finished installing the LED strip lights in
three of my HO passenger cars. Wow,
looks great.
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.
Don
three of my HO passenger cars. Wow,
looks great.
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.
Don