Model Railway Turnout Control Circuit Diagram
This situation persists until C1 is fully charged. No more current flows after that, so the triac does not receive any gate current and switches off. If the input is set low, a negative current flows briefly via C1. It can flow through D2, but not through D1. T4 is switched on now, and the other turnout coil is energised. This circuit takes advantage of the fact that triacs can be triggered by negative as well as positive gate currents. If the turnout coils are energised for too long, you should reduce the value of C1.
If they are not energised long enough, increase the value of C1. The TIC206D can handle several ampères, so it can easily drive just about any type of turnout coil. You can also use a different type of triac if you wish. However, bear in mind that the TIC206 requires only 5 mA of gate current, while most triacs want 50 mA. That will cause the switching times to become quite short, so it may be necessary to reduce the value of R1.
Author: Hans Zijp - Copyright: Elektor Electronics