Model Railway Signal Project
Download PDF version of this page A magnet under the train operates reed switches positioned on the track. The first reed switch changes the signal to red as the train passes, then further along the track a second reed switch changes the signal back to green ready for the next train. The isolated section of track just in front of the signal is switched off by the relay when the signal is red so a train will stop automatically at the red signal. This project uses a 555 bistable circuit. Parts Required resistors: 1k ×2, 33k ×2 capacitors: 220µF 1N4001 diode 1N4148 diode red LED (3mm best) green LED (3mm best) 555 timer IC 8-pin DIL socket for IC push-switch ×2 reed switch ×2 relay SPCO 12V coil miniature magnet - each locomotive needs one stripboard 11 rows × 24 holes Stripboard layout Track connections Connect the reed switches to push-switches A and B (see the stripboard layout). The switches can be held in place between the rails with a small piece of blu tac. Conn...