I have to open/close two wire from a closed device. I cannot open due to it's under warranty, and the only part that I can open and modify is an external button that connects the two wires.
Firstly I wrongly thought that I can simulate the button press ion with only optocoupler (4N25), but thanks to this answer I understood that this piece of hardware is not only an opto-isolator but an opto-transistor: it is better to use a SSR instead (a mechanical relay will not work because of the noisy "tick"). I don't have the GND signal but only Vcc and Vo (thanks to Peter R. Bloomfield for this elucidation).
Just to recap, my needs, I have in one side an Arduino Due that runs at 3.3V. In the other side of the circuit I have a signal that, when closed has 0-6V.
I have seen some other questions about how to simulate a SSR like this and this bit as I got this is not tailored to my case: I don't need a zero-cross detection because I have to drive a DC circuit, and I need to drive it from Arduino Due that runs at 3.3V.
What can I do? Are there some cheap SSR that fit my 3.3V driver and DC lead? Is there some simple opto-isolator that I can use without the GND signal (no opto-transistor)? Or something I can add to the 4N25 that I already tried? Is there some other alternatives that I ignore?
Please sorry my entry level in the electronics so correct me in terminology if I have used unsuitable words.
Best Answer
I have used a Photovoltaic relay for this in an Arduino driven application, the IR PVT312.
It is designed to work as a substitute for a Relay, and is rated to switch up to 250V at 190mA. It is suitable for AC and DC switching.
As you can see from the diagrams below, it's an opto-isolated MOSFET switch.