I have a circuit that uses a 555 timer to generate a 500 msec clock pulse to a 4017 decade counter. The trigger input of the 555 comes from 2 reed switches which come on sequentially. When I tested the circuit on the bench using micro switches with one foot long twisted pair leads, the circuit worked fine. Now it's installed on a train layout and the reed switches are located about 12 to 15 feet from the PCB. Whenever either of the 2 switches is tripped (momentarily closes), the 4017 counter produces erratic counts. The reed switches are wired with twisted pair wires (about 4 twists per inch). Also, there is a .01 mfd cap across each switch. Any ideas?
Thanks,
Walt
Thanks,
Walt