Point Controller
for
5 Servos


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Cost: $20.00 plus $6.50 postage
Kits are available

This projects converts up to 5 points into remotely-controlled points using servos that has been slowed-down to produce a realistic effect. The micro does all the work.

With this project you can convert up to 5 points with slow-acting servos and they can be mounted on the top of your layout or underneath.
When a push button is pressed, the corresponding red LED illuminates to show the point is being changed.
When you turn the module ON, you have to press each of the buttons to activate each point IN BOTH DIRECTIONS so the point is set correctly according to the lights on the module.
This is called "synchronising the module to the points."


 
The module uses a PIC16F628 microcontroller to do all the work.


Switches 2, 3, 4 and 5 (on the module) are connected (the tracks on the PC board) "on the diagonal" so be careful when extending the leads when the switches have been removed. 
You can extend the leads to the switches without removing the tactile switches and this will prevent any problems.


The LEDs and switches have been extended by Graeme Hollis and here is the layout on his control panel.


You can mount the servo beside the track with double-sided tape or in an aluminium housing.

MOUNTING THE SERVO "on the top"
The two photos above show how to connect the servo to the lever of the point. No bracket is available as the servo can be positioned with double-sided tape and then glued in position when the action has been adjusted.
You need to connect the servo to the point with a stiff length of wire called a LINKAGE. (also called a PUSH-ROD)
The servo and the linear actuator produce LINEAR MOTION and the project reduces this linear motion to a very short distance to suit the "THROW" of the point. This is done by reducing the rotation movement of the servo via the program in the micro or the travel of the linear actuator.
This is the distance the point must be moved to change the rail(s) from one position to the other.
The servo produces this motion (distance) via an arm connected to the output shaft and it has a number of holes to so you can get the appropriate "throw."
Connection between the point and the servo is done with a short length of copper or steel wire and this can be called a PUSH ROD, PULL ROD or LINKAGE.
It needs to be straight. It can be bent at the ends so it remains in position.
You need to work out where to position the servo or actuator and then it can be housed in a signal-man's hut as shown in the photos.

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 UNDER-LAYOUT MOUNTING
You can mount the servos under your layout, as shown in the following photos, using a bracket supplied by Talking Electronics.  It comes with two machine screws to hold the servo in place and two wood screws to hold the bracket under your layout. You only need to drill a hole in the base-board of your layout to allow the control rod to activate the point.

The Travel or “throw” of the arm must be adjusted so that the servo naturally stops at the end of its travel and the motor must stop working.
It there is too much tension in the rod (also called lever), the motor will keep working or “hunting “  and this will overheat the regulator transistor on the module.
You can feel the BC338 regulator transistor at any time and if it is hot, there is a “hunting” fault.

Use different holes in the arm to get the right amount of travel.


Turtle bracket comes with 2 machine screws for servo and 2 wood screws and push rod for $2.50

The "push rod" pivots via a 1mm hole in the base of the bracket and the movement of the arm produces a sideways movement via the push rod to the point. The rotation of the servo has been limited to 70° to do this. We are converting a rotary motion of the output of the servo into a forward and reverse motion that is effectively a linear motion.

MORE NOTES:
This projects uses servos that have been slowed down and only rotate about 70 degrees so you can use them to change the position of a point.

The module (containing the electronics) costs $25.00 (built and tested) and you can get special slow- motion servos with 70 degree activation for $2.50 each.
The servos can be mounted on the layout or underneath and each point will cost less than $10.00 when all the parts are included.
This is the cheapest point controller on the market with a press-button to change the point and 2 LEDs to show the position of the point.
You can also get a bracket to hold the servo for under-board mounting for $2.50 extra and 2 metre extension leads for $1.50 extra. You need to order everything together, at the same time, to get the  $6.50 postage.  Contact Colin Mitchell for more details

18/10/2019