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I currently have a garage door opener that has its own controller. One of its inputs supports a mechanical end stop, so it can know when it's done opening.

I'm in the process of adding a very simple circuit (based on a Sonoff, en ESP8266) to be able to control the garage door opener using WiFi. As it's now, I'm triggering the manual "open button" using the relay in the sonoff. It works great, but I'd like to also connect the endstop, so my controller also knows when the door finished opening.

As I understand it, I can't directly plug both circuits to the same endstop, as they use different voltage sources. So my question is: How can I easily "mirror" the endstop, or isolate it somehow, so both circuits can use it?

(adding a secondary endstop is not an option right now, nor is it replacing the main garage door circuit).

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2 Answers 2

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Probably the simplest practical way is to use a relay that has isolated output contacts for circuit A and circuit B. Use the original end-stop switch to activate the relay from a simple power supply such as 12 volts DC. This would need a 12 volt relay.

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  • \$\begingroup\$ I like the simplicity of this. Didn't know there were relays with two isolated output contacts. \$\endgroup\$
    – pgb
    Mar 31, 2021 at 18:29
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You can add an optocoupler circuit, supposing you know both the voltages range. If they are 24VDC, you can get it ready made from the catalog of industrial terminal blocks - many different manufacturers, but they are expensive for what you get. Alternatively you can build on your own

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schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ I haven't measured the garage door yet, but the specs imply it's 12v. As for the ESP8266, it's 3.3v, so I'm not sure this would work. \$\endgroup\$
    – pgb
    Mar 31, 2021 at 18:30

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