Model Boat Mayhem
Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: rayna on December 17, 2020, 06:12:24 pm
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:embarrassed: Hi I have a "360" degree rated servo which rotates one way continuously till the transmitter toggle is reversed then it rotates continuously the other way. With toggle at centre no rotation. All good so far.Now I have fitted a drum to the servo so that it acts as a winch and I want it to do a fixed travel (ie number of rotations one way) then stop and ultimately reverse a number of rotations then stop. From the shore I cannot see when I want to stop or reverse. Can I fit micro switches in the servo circuit somehow so that when the crane hook is at top it stops till I reverse it with the toggle. Suggestions appreciated.Ray
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Hi have you looked at action servo morph at component shop.
John
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:-) Thanks John.Makes an option but maybe I can do a cheaper set up with micro switches controlled by stops on hoist cable/string.thanks for that
Raynor
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I don't know that ACTion unit but questioning whether it will work with your "continuous rotation" servo for the desired end effect as I don't see how the ACTion unit would know the limits. Sounds more to me you already know you have to look at a limit switch -either a simple DPCO switch or a set of microswitches. You might need to open up the base of your servo, remove the small PCB, extend the wires with the external switch in between the PCB and the motor. Actually this is a simple task -might not be explaining it well. there's lots of write-ups out about limit switches for DC motors so probably not worth exact recommendations without more details and perhaps a pic or drawing.
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A "continuous rotation" servo is best regarded as an ESC, motor and gearbox in one unit. The entire idea is that it does not have end stops, or any other internal feedback to tell it where it is currently pointing.
To create them you "can" fit a pair of microswitches operated by the line which short out, or don't, a pair of rectifier diodes. This requires breaking into the case to access the motor wiring.
The simpler alternative is a multi turn winch. If the required length of travel is known, and the diameter of the drum is known, the number of turns required is also known. If the two don't match closely enough, a servomorph or similar can fine tune it by software adjusting the built in end points.
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Rayna,
Have you considered using a multi turn sailwinch?
Glynn Guest
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:-) thanks all. Will take a look at the sailwinch as an option.Ray