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I am asking this question as I'm not too sure how to find a solution (nor how to search).

I am a real beginner in electronics and i need to make a simple circuit using a relay and 2 switches

so the basic functionality should be:

1)When I press button #1, the current goes to the motor, at the end of motor revolution, a mechanical arm pushes button #2 (the current does not stop until a full revolution is made (even if the button #1 is released).

2)When the button #2 is pressed by the arm, the button #1 should cutoff power (even if it's pressed - basically the motor should stop).

I am using a 11.2v li-po battery having 25-50C discharge rate.

What kind of relay do I need and how do I wire it?

Any help or links to answers are appreciated.

[This may be the scheme, im not 100% sure[1]

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  • \$\begingroup\$ It's not that simple... But you should first buy all those components and play with them. Maybe you will succeed, or at least ask more specific question. \$\endgroup\$ – Gregory Kornblum Jan 6 '17 at 21:02
  • \$\begingroup\$ The actual question (sorry i forgot to add it) is, what kind of relay do i need and how do I wire it? \$\endgroup\$ – Radu Alexandru Jan 6 '17 at 21:12
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    \$\begingroup\$ Google motor start stop relay circuit. \$\endgroup\$ – Andy aka Jan 6 '17 at 21:28
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    \$\begingroup\$ Possible duplicate of Relay circuit with off switch \$\endgroup\$ – Voltage Spike Jan 6 '17 at 21:32
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    \$\begingroup\$ You could also drawn a circuit schematic for the circuit you are describing here. It would be easier to understand. \$\endgroup\$ – Keno Jan 6 '17 at 21:32
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enter image description here

I think what you are describing requires a motor start stop circuit. The only thing you have to figure next is what to do once the motor stops. With the circuit above it just does nothing because the motor rotor is positioned to press the stop button. It can be arranged to allow the start button to restart the motor and, with some extra engineering pressing the start could reverse the motor back to the beginning. You need to pay attention to precisely what you expect to happen in all stable and transient states. Nobody can tell you what to do, you have to decide but, regarding your original question, this is, I believe an answer.

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Sounds like a classic windshield wiper problem.

No matter what your electronic solution is, you'll need a mechanical switch to tell you when the motor is at home position. In this sense you are stuck with cam controls as it were.

So... Instead of switch #2 saying it's home, have the switch say it's not home. To do this, use a normally-closed switch -- this switch is connected at all times, and disconnects when it is pushed.

This makes it really simple. The not-home switch (#2) goes in parallel with the user's "start" switch (#1). The motor runs on either one closed.

Now the logic is:

  • if the motor is not home, run.
  • if the button is being pushed, run.

So a user button press will run the motor off-home, at which point the not-home switch will close, and it will run until it is back home.

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  • \$\begingroup\$ Actually, when the motor is 99% home, the button gets pressed. \$\endgroup\$ – Radu Alexandru Jan 7 '17 at 9:00
  • \$\begingroup\$ Let me make more sense out of it, when the motor spins, it turns a gear, which has a lower arm that pushes switch #2 when the gear is "home", simple as that, but the arm is only 2mm long so as long as motor stops right on the arm, theres no problem using your solution. Just don't know what to do \$\endgroup\$ – Radu Alexandru Jan 7 '17 at 9:17
  • \$\begingroup\$ In my solution, once the arm gets near home and pushes the button, motor power will be knocked out so it won't be able to advance past the arm. Unless the user is holding down his start button. To be clear, I am recommending a normally-closed switch for the arm -- this works inverse, it connects at all times, and disconnects while pushed. \$\endgroup\$ – Harper - Reinstate Monica Jan 7 '17 at 19:00
  • \$\begingroup\$ Sounds right. The only problem i have right now is making a full cicle with a simple push and release instead push and hold till it stops \$\endgroup\$ – Radu Alexandru Jan 8 '17 at 4:44
  • \$\begingroup\$ I've ordered a snall pcb board with 2x mosfets and on/off signal, hope it will do the trick \$\endgroup\$ – Radu Alexandru Jan 8 '17 at 4:45

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