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Pointwork Control Example Servo

DocRef: JC3a

Control using Servo Motors.

A (relatively) low cost method of point control is through the use of servo motors (as used in radio control applications). Servo motors vary widely in specification and price according to the amount of torque they can produce, whether they have plastic or metal gears and the degree of weatherproofing. They do require a digital control board to function and the radio control lead fitted to servos needs to be compatible with the control board output pins.

Typical servo shown below, fitted to an aluminium bracket for sub-baseboard mounting on an exhibition layout and with operating arm attached.

The digital control unit shown here is a Mega Points control which will operate both pointwork and semaphore signals (there is even a built-in signal arm "bounce" function). Each output needs to be programmed (using the built-in buttons) to suit the range of movement of the particular item being powered.

If (as with the Gauge 3 Society exhibition layout "Monkton Priors", which is the example used here) the layout is for indoor use, then weatherproofing does not enter into the equation and both servos and the digital control circuit boards require minimal protection from mechanical damage. If you plan to use this method in the garden (or an outbuilding where humidity and condensation come into play) then serious consideration needs to be given to protection against moisture or the components will rapidly deteriorate; the expensive electronic control boards will likely be the first to fail.

With servo motors, the element being powered must be free to move freely between the set limits. If any excessive resistance is met, there is a real risk that the motor will burn out, since power remains applied until the pre-programmed limit has been reached.

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Page last modified on February 27, 2018, at 10:39 PM