Since I model a subway-elevated line like those in New York, Philadelphia, and Chicago, I've been installing lineside block signals. Does anybody here have working signals on their layout? If so, are they Type-D (vertical row of green-over-yellow-over red); Type-G (upside-down triangle of green-and-yellow-over-red); or semaphore (either upper or lower quadrant)?
I have a number of searchlight type signals, both single and multihead, on my H0 railway layout. They work, but only to indicate turnout positions.
I am currently using the Bachmann Block Signals (Part #42101) and removing the green/red plastic lenses and replacing them with green and red LEDs. I first strip down the signals, removing the lenses and ladder.
I carefully ream out the lens openings to accept the LEDs. I common together the longer of the two leads from both the LEDs and solder a short
piece of thin white wire to the common lead. (Radio Shack sells small spools
of blue, white and red circuit board wre that works very well) I then solder
a piece of blue wire to the Green LED and a piece of Red wire to the Red LED. Once the wires are all soldered to the LEDS, I cut off the excess LED leads and paint the backs of the LEDs with black paint. (this hides the LED light from glowing out the back of the signal. When the paint is dry, I drill a small hole in the signal's base, between the signal shaft and the ladder support holes, and cut a small piece of heat shrink tubing to fit between
the base and the signal head. This tubing will help hide the signal wires.
Once you reinstall the ladder, you won't see the wires inside the heat shrink. Connect a 1000 ohm resistor (1k ohm) to the end of the white wire.
This will limit the current to both LEDs. With a C or D sized battery, connect
the white lead and the green lead to the battery terminals to test the LED.
(If the LED does not light, swap the wires to the battery and the green LED
should light.) I am using a 5 vdc regulated power supply to power all my signals that are controlled by Block Relays. (Yes, I am running DC not DCC)
I'm using the Bachmann three-light Type-D color light signals, but with Atlas Snap Relays powered from an AC transformer. My subway trains have a "third rail" shoe mounted on the trucks, that activate a set of contact rails on each side of the track, as a train passes by. It's a simple ABS (Automatic Block Signal) system similar to used for decades on New York and Philadelphia subway lines, with a train resetting the previous siganl it passed to yellow, and the one before that to green, as it trip's each signal it passes, to red.