All,
I am looking for a solution on actuating this stall motor switch machine for my train layout.
I currently have a several PCA9685 16 channel servo drivers and would like to utilize the control from these driver boards.
Will this “RC Servo Switch” work? I basically need a double pole double throw to reverse the stall motor switch machine back and forth.
Thank you!
Kennedy
What is a "stall motor"? Any datasheet available?
It is a two wire motor that moves to its stopping point and holds under load and power against the stop. Reverse the wires and it moves the other direction against its stop. The linkage is used to move track switches at a smooth slow rate.
What If I use this double relay to reverse polarity on the switch machine?
LICHIFIT Q1 RC Aircraft Relay Switch PWM Model Remote Control for Drone FPV Quadcopter Launch Spare Parts https://a.co/d/2vMqGZf
The schematic would look like this.
I guess the Servo driver boards would switch this relay board with no problem?
An H-bridge seems a much more economic option.
This board can control four motors.
Not sure where the PCA9685 could fit in.
Leo..
That link just gives a blink on the screen.
A stalled motor will, as I see it, overheat. Better use a servo.
Maybe not that one.
The datasheet tells me that the motor stalls at 15-16mA on a 12volt supply.
A 9volt supply and that L9110 board could be the solution.
The Arduino could be coded to stop powering the motor after some time has passed.
Leo..
Okey. The datasheet didn't download on the tablet by some onknown reason.
It sounds like the "stall motor" is just a low-current DC gearmotor, perhaps with internal limit switches, so you should be able to control it with an H-bridge. Yes, you could use an RC servo control and a DPDT RC relay, but I'd be hard pressed for a reason to do it that way.
Thats correct, just a geared motor. How are H Bridges usually triggered? All I have is a servo PWM signal.
Please confirm the impression I got from as much googling as I am going to do that…
…these stall motors are tolerant of being continuously driven against their physical ability to move to keep what they are moving firmly in one or the other extreme position.
a7
Yes sir. That’s exactly how they work.
I would try an 8-channel I2C I/O expander with the 4-channel board I linked to.
Much smaller/easier than trying to use a PCA9685 board as digital I/O.
Leo..
Yes. Those stall motors are commonly referred to by the term "Tortoise", their product name, and are used in literally thousands of model railroads for turnout control; they can be powered continuously from 12VDC without damage. They can be controlled with a DPDT reverser, or with an SPDT switch if you have both +12V and -12V available. There are oodles of pushbutton control circuits out there, as well. Often, a bipolar red/green LED is wired in series to show the (often distant) turnout state, though it's less necessary if you use a toggle switch. The LED can also be wired in parallel with the stall motor, but that does increase the current load on the 12VDC power.
Or with an H-bridge.
Leo..
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