This project
controls a set of points, using a miniature LINEAR ACTIVATOR. |
POINT CONTROLLER for LINEAR ACTUATOR (the relay to
power the frog rails is not included in the kit)
The Linear Actuator is very small and ideal for this application.
These features are contained in our simple design and can be built in an evening. A kit of components is available from Talking Electronics as well as a pre-programmed microcontroller.
LINEAR ACTUATORS
There are a number of beautifully-designed LINEAR ACTUATORS on eBay and one design accepts commands identical to SERVOS, but they cost twice as much as a servo.
This Linear Actuator is available from Waltzmart.com for $11.00 with free shipping. You get 2 Linear Actuators for $11.00
SLOW-MOTION
WIRING THE LINEAR ACTUATOR Linear Actuators come with different colours on the 3-pin connector:
THE CONTROL LINE The control line is called the "signal Line" and requires a waveform that is classified as a DIGITAL SIGNAL. This means it must rise to about 5v and down to about 0v to for the circuit inside the servo to respond. The time when the signal is high is called the MARK and the low time is called the SPACE. The width of the MARK determines the position of the output and it only takes a few cycles for the servo to respond and drive the motor to the angular location where the received signal matches the signal from the input potentiometer. The signal on the control line is called PULSE CODED MODULATION and the HIGH will vary from 0.5mS to 2.5mS. The LOW time needs to b e about 20mS. This means the coded signal arrives at about 50 cycles per second (50Hz).
5/5/2014 |