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There is a machine which usually runs in standby mode, and the only way to wake it up is by pressing a physical button with a small force and then quickly release.

I want to remotely push the button using a Pi as a controller, could you please give me an advice how to make a pusher?

  • en.wikipedia.org/wiki/Linear_actuator Most likely needs to be driven with a motor. – goldilocks Jun 18 at 15:34
  • Raspberry Pi is probably overkill for this, BTW. Arduino or a variant might be a better choice. But Raspberry Pi certainly could be used for this. – Brick Jun 18 at 16:24
  • @goldilocks thanks, a smaller version is call push-pull solenoid, which is what I need. – b1105029 Jun 18 at 17:08
  • Ah, let me see. You have an idle machine which can be started by a human hand pushing a mechanical switch for a short while, say 0.2 seconds. Now you want a clever robot hand to replace the stupid human hand. I agree that one way is to uses a solenoid. I actually tried it before. The problem is that you need to fix the solenoid right on top or beside the button, and secure it without slipping while the machine is moving, perhaps with much vibration. It is not an easy mechanical job (I studied metal work in school and passed with distinction. I also got a mini mechanical workshop at home! – tlfong01 Jun 19 at 1:57
  • So I think what @rpseu suggests is simple, practical, and the best to explore. You just extract two wires from the two contact points of the button. The two wires goes to where Rpi sits. If the machine is making a lot of electrical noise, you might need to do some optical isolation (check out how optically isolated 5V relays are doing this) and also logical level shifting if the button is using 5V/12V which will fry Rpi if directly connected to its GPIO pins. – tlfong01 Jun 19 at 2:03
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If you want an actual button pusher for educational/entertainment needs, then you can ignore this answer.

Given your description, I would assume that this physical button is a normally open push button (NOPB) with two wires going to it. In this case, I would think you could come up with a simpler solution that involves tapping one or both of those wires. For instance:

If one of the wires is a common wire that goes to ground, a Pi output pin configured to ground the other wire might be sufficient (with grounds bonded between the Pi and the device in question). If neither wire goes to ground, but I am still correct about the NOPB, it should still be simpler to control some other sort of normally open contact between those two wires in parallel with the button so that a human can still press the button, but the Pi simply briefly connects the wires together without the button.

  • I once spent some 50 hours playing with electrical mechanical solenoids and thought I was good at it. So I used it as a "hammer" for many solutions. Of course stupid me got LOL at by my DIY friends. – tlfong01 Jun 19 at 2:09

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