Signal Control Relay

EM131 Series 

Relay Cards 

as used in Model Railway Layouts

These relay boards are used to control signal lights and isolate tracks at a set of points

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. 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.

We now sell the sensor part as a kit which can be used for the above or to indicate Train movement on the track in hidden areas like tunnels etc.
The Kit is MR200 at £2.10.

Magnets		SW932 This is a 6mm diameter by 2mm high magnet with a small indent on one side to indicate the North side.
		SW933 This is a 3mm diameter by 2mm high magnet with a small indent on one side to indicate the North side.
Sensor Switches		SW927 Encapsulated magnetic reed switches, Normally  open contact. Switching current 100mA. Size 15mm long, 3.2mm wide, 4.2mm high. Lead spacing 12mm. Operating Distance 5 to 12mm.
		SW926 Encapsulated magnetic reed switches, Normally  open contact. Switching current 500mA. Size 20mm long, 3.2mm wide, 4.2mm high. Lead spacing 18mm. Operating Distance 5 to 18mm.
		SW929 Encapsulated magnetic reed switches, Changeover contact. Switching current 500mA. Size 20mm long, 3.2mm wide, 4.2mm high. Lead spacing 18mm. Operating Distance 5 to 18mm.
		SWP100 Peco type changeover leaf switch, used for points sensor.
		SW054 V4 type ultra-miniature microswitches with roller actuator. S.P.D.T Switching. Ideal for all position sensing. If fitted between rails will be activated by train passing over.
		SW052 V4 type ultra-miniature microswitches with blade actuator. S.P.D.T Switching. Ideal for all position sensing. If fitted between rails will be activated by train passing over.
Control Switches		SW301 A miniature toggle switch with 2 momentary ON positions. The configuration is (ON)-OFF-(ON), brackets indicate momentary. Up switches the point motor one way for as long as you hold it, no longer than 1 second, it then springs back to OFF when released.
		SW310 A double pole miniature toggle switch with 2 momentary ON positions. The configuration is (ON)-OFF-(ON), brackets indicate momentary. Operates the same as SW301, but can operate 2 sets of points at the same time – Crossover points or loop points.
		SW305 A miniature toggle switch with ON-ON or ON-OFF operation. Used for light signals Red and Green. Connect +v to centre and Red to one side and Green to the other. Do not use this switch with semaphore signals.
		SW315 A double pole miniature toggle switch with ON-ON or ON-OFF operation. Used for light signals Red and Green. Connect +v to centre and Red to one side and Green to the other. Controls 2 sets of lights Do not use this switch with semaphore signals.