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EM135 Points & Signal Control

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Simple Set of Points with Signals on both tracks.

In this set up direction of travel is from left to right, so we need to control signal A and signal B at the same time so they have the correct aspect at all times. The magnet SW933 is glued to the moving arm of the point assembly (See Fig: A) . The reed switch SW926, SW927 or SW929 is placed within 10mm of the arm when the points are set to straight through, thereby activating the relay.  Not too close otherwise it will remain activated when the points change.
Please note the wiring of the relay contacts. The Normally Closed contact on the left side of the relay power the signal on the straight through line and therefore shows GREEN. The right hand side contact power the  Junction Line and the Normally Closed contact is powering the RED signal. When the Points are changed the relay will be activated the signal lights will change aspect.
If you were to use the double relay board, you could isolate the junction track from power when the points were in the straight through position, with the second relay.                                        
  Fig: A
With the points in the position shown move the Reed Sensor toward the magnet until it makes/clicks, then move it away 5mm and fix in position. Activate the points now to check that the Reed Switch is working correctly. There are many other types of sensors/switches available for you to use.
For other types of sensors see our ' Sensors Types for Layouts ' in the Useful Section.