controls a set of points with a SERVO.
TURTLE POINT CONTROLLER
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.
Comparison of the TORTOISE™ Slow Motion Switch Machine with BluePoint.
We've had a number of people ask about the price of a TORTOISE™ Slow Motion Switch Machine compared with Blue Points™, so here is a quick comparison. The BluePoint is smaller, cheaper and has a better tag board for connecting the wires.
Comparison of prices for converting from manual to automatic:
Turtle Point Controller project suits either a LINEAR ACTUATOR or R/C SERVO. Both devices move proportionally to the signal received via the signal line. Both have an IC that receives the signal and produces a pulse to the motor to turn it either clockwise or anticlockwise and compares a signal received from a pot or linear resistor to determine the angular or linear position of the arm. It does not work with TORTOISE™ or Blue Point™ controllers.
There are a number of beautifully-designed LINEAR ACTUATORS on eBay and one design accepts commands identical to R/C 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
A Remote Control SERVO is the cheapest way to control a set of points.
This project operates the servo slowly to get the effect of a TORTOISE CONTROLLER with the advantage of placing the servo next to the track so you don't have to cut a hole in the layout or any other awkward installation. It is also much cheaper than any other controller.
This is one of the servo's we tested. We call it MEDIUM SIZE. The LARGE servos are too big for this application.
Here is the SMALL SERVO. It uses a micro motor. A Micro Motor is
The all-plastic versions are much cheaper and have
a very similar compound gearbox to reduce the
motor RPM and increase the torque.
A Micro Motor operates just like a 3-pole motor.
The winding is "skewed" (twisted) to produce
smooth rotational torque.
The servo in the kit is the MEDIUM SIZE and comes with a set of HORNS. These are commonly
called CRANKS or ARMS or LEVERS and connect to the output shaft with a splined connection (grooved) to prevent the arm slipping on the shaft.
Some come with a screw to hold the arm in place.
Single Horn or Arm
Star or Cross
Double Horn or Arm
Using a "Star" or "Cross" to produce a linkage to operate the points with the servo near the track:
The project is designed to produce about 90 degrees of rotation for the servo. This produces enough "throw" to move the rails.
Here is a photo of the components in a servo from HOW AN R/C SERVO WORKS:
A Block Diagram of the electronics:
Most servos will rotate up to 180° and some will rotate to nearly 270°. Our project only needs about 45 degrees rotation to produce a THROW of about 10-12mm when a push-rod is connected to a hole near the axle. The track-points for HO gauge only need 8mm throw and this can be obtained very easily by connecting to a crank on the output of a servo.
WIRING THE SERVO
Servos come with different colours on the 3-pin connector: