I’d like to make a control using the HSR-1425CR (57 oz.in.) Continuous Rotation Standard Servo. It’s function is to rotate a lens ring one rotation. . I know very little about servos and nothing about these RC type servos. I’d like to control this servo by wire (wireless is not necessary, not preferred). Ideally, I have a rotary device (pot, encoder) that makes 1 turn for 1 turn of the lens ring with absolute repeatability (the position of the pot/encoder is locked to the position of the lens ring). The quieter the function, the better
Can someone point me to the right devices to connect to this item to do this function? Something simple. Something small.
But I’m not sure if the CR servo is really going to work the way you think it will. The CR servo has no position feedback and can easily try to rotate past the lenses ability to move. (past a physical stop) You really need to wire the pot into the control board of the servo to gain the ability to move to a certain position. I’m not sure if you can find the place to attach the pot on the CR servo, as it’s been made CR at the factory. However you can go back to modifying an HS-422 servo for CR and connect your pot to it.
Servo motor output connects to lense assembly
Pot connects to servo motor PC board in place of the one inside the servo.
Servo control wire plugs into servo controller with knob.
As long as motor movement direction is correct, when knob is moved on the controller the servo motor moves the lens, and the potentiometer sees the movement and the servo control board stops the motor when the lens is in the right position.
Thanks Jim. Excuse my ignorance; Can I get the servo to rotate more than one revolution by having the external pot?
I might need the servo to rotate 3 times for one rotation of the controller dial. Is that possible through use of the external pot?
Thanks for showing me your controller.
Is this servo relatively quiet compared to a stepper? I do plan to box it all up and use remote microphones, but I still don’t think the noise of a stepper would be tollerable no matter how much I try to silence it.
Yes that’s the whole point of using the cont. rot. servo.
I can’t answer this question. Do all steppers have the same volume of noise? Did you want me to compare the sound of a servo to a specific stepper? At what volume, dB is too much? Is audible sound the problem, or is some mechanical transmission of sound the problem. I have no instruments to accurately measure sound.
No reason for a small (NEMA #17) stepper to be noisy. There are resonance bands that you need to avoid, but unless you are building a high-performance system, I doubt you’d run into problems. And the stepper drivers I do buy for a high-performance system microstep to avoid the resonance problem.
Actually, your best bet for a camera focus is a small geared DC servo (not R/C) motor, and encoder.
But I don’t recall you saying what camera you had to focus…
I’m not familiar with your servo, but if it has two resistors installed in place of the usual pot, you may be able to just remove the resistors and connect the pot that is mounted on your lens ring in place of the resistors. You would still need to attach some type of drive connection between the lens ring and the servo (could be a simple friction drive).
