Servo Tester Modified:

 

Servo Tester, readily available and ripe for modification and connecting to a DCC decoder.

Do check with the vendor before purchasing, their are least two variants available, one which upon power on, will go through the complete test routine including moving any attached Servos, this one is best avoided, and go for the other type, which upon power on does not 'cycle' through the routines.

Modification of the Servo Tester, requires soldering two wires to the underside of the PCB.

One wire to the middle connection of the Potentiometer, and the other to the GND connection.

The two wires can then be connected to a On/Off switch, or a Optocoupler. 

To operate the Servo, by closing the switch, the connection to GND is complete, Servo moves to the end point position as set by the Potentiometer on the Servo Tester. 

By opening the switch, Servo moves back to it's starting position. 

RECOM, data sheet about the switching voltage regulator.

Individual parts, amalgamated and built on a single Strip board PCB. 

Optocoupler, for connection between decoder output, to input of the modified Servo Tester.

Switch action of opening and closing is replaced by the LGB 55021 Function Output connected to the Optocoupler, activation by the F1 Key on the Handset. 

Function Key pressed as in ON, Servo moves to the end point as set, Function Key pressed again, Servo returns to the start point.

Host decoder is a LGB 55021, which has no onboard facilities to control a Servo.

Alternative ideas to assist with construction:

5V regulated power supplies, can be found here about the LM2596 module and here on the Recom switching voltage regulator.

Optocoupler Module.

Only provision on the one above, that for long term continuous use, the 3.3K Ohm will get warm, may need to change it out for a resistor with a higher Watt rating. 

DCC controlled Modified Servo Tester to operate a four phase Orange Beacon Light. 

Short video to show the four types of lighting effect for a rotating Beacon.

Idea borrowed for the Modified Servo Tester from a Blog Posting by Rik of the Peckforton Light Railway. Operating points remotely with servo testers