Rod Stewart posted:...
I have my first few cars done using grj's roll your own modules with R1 of 12 ohms and R2 of 50 ohms. This gives an output range of about 12 to 100 ma. The cars are 15" so I am using 14" long led strips, with 21 leds per car. For a first run I have them set at 90 ma output, so just over 4 ma each, and they are quite bright.
If you're using the standard 12V LED strips, note that they are 2" (5 cm) sections of 3 LEDs...with each LED within a section receiving the same current. So your 14" strip is being split into 7 x 2" sections with each section driven by about 13 mA (90 mA / 7). Hence each LED is also 13 mA. And, as you and others have reported, 13 mA LED current is mighty bright for O-gauge passenger car LED strips.
Rod Stewart posted:...
In thinking about the photocell variable brightness idea, I guess it would be overkill and unnecessarily complex. Plus everytime the train went under a bridge or through a tunnel the lights would dim, which would look kind of odd.
I don't think $1 for a few generic parts (photocell, 2 resistors, 1 transistor) is complex...especially if it attaches to the LED strip with just 2 wires. Ironically, by using a 5 cent capacitor like on GRJ's lighting module, you can implement flicker rejection on the photocell circuit. In other words, it would average the ambient lighting over many seconds or even minutes. So short term variations don't change the LED brightness.
Junior posted:Hey Stan.....you absolutely CRACK ME UP! I've been educating myself (reading all your fantastic post RE. Track Occupancy) to use them to trigger Atlas Signal System. Your posts are absolutely outstanding!
Well, as long as you're laughing WITH me and not AT me! 
