I have a DC geared motor with 1 hall effect encoder and I'd like to find the pinout to use it. Unfortunately I don't have the data sheet and since all motors have different pinout, the only option I have is to find it via multimeter.

I know the ground pin, but don't know which ones are Motor A B, +5V, and encoder output.

Is there a way? Thanks!

Edit: Adding photos of the motor enter image description here enter image description here

Edit2: Diode and resistance readings between Gnd Blue and Orange pin(5V and encoder output, which is which unknown)

gnd to blue: connected, 662ohms blue to gnd: not connected

gnd to orange: not connected orange to gnd: connected, 1641ohms

blue to orange: not connected orange to blue: not connected

  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$
    – Voltage Spike
    Feb 23, 2021 at 18:05

1 Answer 1


The two large solder blobs either side of the encoder wheel are the motor terminals. These appear to be going to the black and red wires via B2 and B3 (which are probably low value inductors used to block brush noise). Connect your multimeter to these wires and measure resistance, which should be a few ohms. Then measure DC volts while spinning the motor by hand, which should produce a small voltage whose polarity depends on the motor direction.

The other 3 wires are the Hall effect ground, power supply, and output signal. You have already determined that the brown wire is ground, which makes sense because it has a thick trace going off it. B1 and C5 are probably a power supply filter, so put your meter on continuity test measure between B1 and the Orange and blue wires. One of these should be a direct connection to B1. I'm betting on Orange because the blue wire appears to go to R1, which would then make it the signal wire.

  • \$\begingroup\$ Thanks @bruce-abbott B1 and orange wire are indeed shorted. So would that be 5V? You wonderfully reverse engineered the pins. As a followup question, why is the ground trace thicker? Also, how did you identify B1 and C5 are power supply filter? \$\endgroup\$
    – jash
    Feb 24, 2021 at 7:41
  • \$\begingroup\$ 5V is the likely supply voltage for a Hall sensor. Ground traces are generally thicker to reduce voltages across them due to current flowing in the ground. Most analog signals are referenced to ground, so low ground noise is important. Signal wires are usually thinner because they carry low current. B1 appears to be an inductor, so with C5 it would form a low pass filter. This is commonly applied to analog supply rails to block noise coming from the voltage source. \$\endgroup\$ Feb 24, 2021 at 7:56
  • \$\begingroup\$ Thanks for your incredible help and teachings! Made me a better at electronics today! \$\endgroup\$
    – jash
    Feb 24, 2021 at 10:26

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