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I would like to play around with this servo motor but I'm not sure what the feedback mechanism on it is or what the interface is.

The mechanism has 3 wires leading to it (yellow, orange, brown). It consists of a hard black disc (I think the disc is metal or possibly a ceramic?), a PCB behind it that has a square wave pattern around the circumference of the board, and on the board itself there are a couple resistors, ceramic capacitors and a single 8 pin IC (I can't see what is on the IC, I don't want to take the mechanism apart).

The motor came from an old photocopier.

My best guess is that it might be a magnetic resolver but I've never had any experience with them.

So the question is: What is the mechanism in the picture and how would I go about interfacing it (ie, if it was an encoder, I'd do quadrature decoding ect).

motor

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  • \$\begingroup\$ Three wires for just the sensor, or for the sensor and motor? \$\endgroup\$
    – Nick T
    Commented May 2, 2011 at 12:09
  • \$\begingroup\$ He stated that the feedback mechanism has three wires! \$\endgroup\$
    – Leon Heller
    Commented May 2, 2011 at 12:23
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    \$\begingroup\$ Total of five wires. 2 got the motor and 3 for the sensor. \$\endgroup\$
    – Faken
    Commented May 2, 2011 at 12:24
  • \$\begingroup\$ any evidence of permanent magnets in that rotor? \$\endgroup\$
    – JustJeff
    Commented May 2, 2011 at 21:50
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    \$\begingroup\$ @JustJeff: Sure thing:(1st line) DC-5216-053 (2nd line) DC24V 1.65A 1200r.p.m. (3rd line) 12Gq 80011 (4th line) 54031 (5th line) SHINANO KENSHI CO.,LTD. MADE IN JAPAN. I tried googling the model number and looking it up on the manufacturer website but I found nothing. \$\endgroup\$
    – Faken
    Commented May 4, 2011 at 2:33

3 Answers 3

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With just three wires, I don't see how it can supply a quadrature output. For that, a supply for the IC, ground, and two wires for the quadrature outputs would be required. It's probably just a tacho.

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  • \$\begingroup\$ Any idea what kind of interface it would be? Analog voltage? Sine waves? \$\endgroup\$
    – Faken
    Commented May 2, 2011 at 21:35
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    \$\begingroup\$ @Faken - probably one line is a ground, another is excitation (might be DC, might be AC), and the 3rd line is some kind of sense signal, that will just give you speed. \$\endgroup\$
    – JustJeff
    Commented May 2, 2011 at 23:43
  • \$\begingroup\$ Tachometers are analog voltage proportional to the rotational speed of the shaft. \$\endgroup\$
    – AngryEE
    Commented Jul 30, 2012 at 17:00
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In fact that is a single channel encoder. Maybe optical or magnetic (hall sensored). 3 wires encoders are always: 5vdc input, gnd input and pulse output.-

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The output is only a speed feedback.

Magnetic pickup on the PCB tracks, with the magnetic disk mounted on the shaft.

Some type of comparator circuit with the TA75393P dual comparator.

photo of PCB track side

photo of PCB component side

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