Using Servo feedback line WITHOUT power to servo

Other Hardware Motors, Mechanics, Power and CNC
1

Hello,

My first post on this forum, I hope to make it well..

I'm building a metal geared servo based 6DOF arm, that allows the operator to manually manipulate the arm angles and positions, the "record" key positions, and later "play" the positions as a sequence.
Arm and servos work well, controlled by the R3 Arduino. The servos are non-branded, no datasheet or any other info - they have metal gears, and no feedback line - so I hacked one to output a feedback (images attached), it works great when servo is powered, and after detaching PWM signal, I can move the servo gear and "record" the angle.
However, I prefer to have the servo to be POWERED OFF when manipulating it - it is much easier to move the gears, of course, and I believe will do less harm on the long run.
Can anyone suggest the best way to connect the feedback line in this scenario?
I've tried to define the Input as PULLUP, so when the servo GND is attached to the board, I can get a read - but it is in low resolution, and of course when moving the motor, it generates voltage that interfere the reading (is a diode required?).

Thank in advance

servo2
servo2800×1600 90.7 KB

2

You want to read a devices electrical feedback without using electrical power?

You could build an electronic circuit... Nope that would use power.

3

I want to measure the servo position, without giving power to the motor.
So it will be easier to move the gear.
Maybe I can use the servo's potentiometer as a, well, a potentiometer. But not fully understanding the inner connections of the servo, I'm not sure how to do that.

SO I ASK FOR HELP.

I hope it was a better description for my question.

4

Pots have three pins. Connect the ones on the far side to power and ground and connect the middle one to an analog pin.

5

OR, you could use the scheme that has been a standard for years. That is to enter a "program" mode and record the movements being made by the servos as they are doing the movements at your command. Then you have a file of all the movements in order. You also will need to record the timing between movements so your play-back will be closer to the real movements you recorded.