How to Wire Plasticville signal bridge for operation

There are plenty of schematics for building a simple signal circuit on the web, or you can find ones already made for you to install. Decades ago I built the signal circuits shown in a book called Electronic Circuits for Model Railroads published by Model Railroader. I made four or these simple circuits and set them up on the layout under Plasticville Signal Bridges into which I had installed low power grain of wheat bulbs. The project could also be done with LED's which are much cooler. Operation was achieved by placing a small magnetic reed switch between the rails which was tripped by a small magnet attached to the bottom of the loco. As the switch was tripped, the signal light above went to red while the one across the layout went green. When the train passed under the signal bridge across the layout it turned red and the original went back to green. Two track operation simply required a set of circuits for each track and related signal. The hard part today is finding the simple transistor and resistors. Used to be able to just go to Radio Shack, but now you cannot get anything there, hence they are closing many stores.

Gandy

I would be interested in seeing the results of your efforts.  I had one of these since childhood that was barely hanging on.  Rather than make it an operating unit I changed the lenses to yellow (had some from who knows where) and wired small bulbs in.  It serves a station so amber all the time seems to work and the light lets me know when I forget to kill the transformer power.

Maybe you can buy some small LED lights at Radio Shack and install them and use a double pole double throw switch, center off, to change colors. Take you light mount with you to see if the lights will fit into it.

I have an older Lionel signal light that I use and cut a section of track, the outside rail, to get the red light to come on, green stays on as I wired the signal's common to the powered rail and use the outside rails for light changing.. When a train passes through the red light comes on and lets me know the block is occupied.

Lee Fritz

5 mm LEDs fit the signal head - Always thought about making these operational

Marty Fitzhenry used LED's for the ones on his layout.  Notice the signal bridge on the right.