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I have been building a new controller unit for a ~20 years old gate opener because it was never reliable, and eventually stopped working entirely.

So far, I have got everything working except from stopping the motors at the correct time. The motor has 5 wires, two for 24VDC for powering the motor, two 12VDC for powering a "pulse generator", and a single "pulse generator" wire.

I was not able to figure out what kind of signal this pulse generator delivers, so I started off by just starting the motor, waiting for some time and then stopping it. However, I realized that this desynchronizes really quickly which results in the gate hitting the wall or not closing correctly.

So I tried analyzing the signal from the pulse generator, because the old board could do this starting and stopping precisely. It is a 10 kHz squarewave signal, but no matter how hard I tried stopping the motor, it never changed in frequency or duty cycle, but that may be due to my 30€ oscilloscope from ebay. I also observed that the original board would refuse to boot if the pulse cable was disconnected. When the cable was removed while the motor was moving, the motor more or less stopped.

Has anybody had experience with such circuits / signals?

If it helps, I have got the users manual of the original controller ("Einhell FA-G 2601").

The owners manual can be found here.

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  • \$\begingroup\$ Welcome to EE.SE! This appears to be a reverse engineering, modification, or repair question. Please be aware that such questions must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being discussed, so that you can ask specific, focused questions that can be answered concisely. Otherwise, the question is far too broad. More information can be found here: Is asking how to fix a faulty circuit on topic?. \$\endgroup\$
    – Dave Tweed
    Jun 24, 2019 at 19:55
  • \$\begingroup\$ @DaveTweed I think I have some understanding on how the device is working, but I can't figure out the signal. I think I could be missing some common PWM singal or something. The owners manual can be found here smolka-berlin.de/includes/download_pdf.php?ID=228 \$\endgroup\$
    – Twometer
    Jun 24, 2019 at 19:58
  • \$\begingroup\$ There's no real reason to think that the pulses change character in any way. It's much more likely that each pulse represents a certain increment of motion by the motor, and that the controller board is simply counting the pulses in order to determine whether the motor has moved far enough. The "teaching" procedure outlined in the user manual would be consistent with this interpretation. \$\endgroup\$
    – Dave Tweed
    Jun 24, 2019 at 20:10
  • \$\begingroup\$ @DaveTweed ohhh that makes so much more sense, I am gonna try this. But shouldn't the frequency change then if the motor was movingn slower? \$\endgroup\$
    – Twometer
    Jun 24, 2019 at 20:14
  • \$\begingroup\$ Yes, but your description is so vague I wasn't sure that it doesn't change. It's also possible that it is something like a variable-reluctance sensor, in which case, you would be looking for amplitude modulation of the pulses, where one cycle of modulation represents an increment of motor motion. \$\endgroup\$
    – Dave Tweed
    Jun 24, 2019 at 20:27

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