Bluetooth speaker ground wire connected to 4N25

Thread Starter


Joined Mar 20, 2009
I am wondering if I can use a 4N25 optocoupler to turn on/off two small speakers. The reason for doing this is that when I turn on the unit, I won't have to hear "device connected". Side note: it's connecting with Bluetooth to my Amazon Echo Dot.

I currently have an Arduino checking for voltage on the LED that's in it. It has red, blue, orange and green. The blue has the highest volts at 2.1vdc while the red has 1.3vdc. That's how I determine if it has gone to sleep or not:

red = off/stand-by/sleep mode
blue = bluetooth
orange = usb
green = optical
Would I be able to hook both the right and left ground wires to one of these?

My thought is to turn the sound off during the time it reconnects to the Bluetooth (the "device connected") so that whenever it goes into sleep mode I can wake it up again without having to hear it, and then re-connect the ground wires back after a few seconds. This will happen after 10 minutes of sound not playing via the Amazon Echo Dot.

That's just how this Bluetooth speaker operates, which I dislike, but I don't want to purchase another one thinking that it too will have some sort of sleep mode, plus it's just more money to spend.

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I am open to any other suggestion on how to do this some other way. This is just the only way I know how to combat this issue.


Joined Jul 10, 2017
The 4N25 is not suitable for this application. With maximum LED current, the maximum Ice is around 30 mA which is far too small for driving a speaker. The other problem is that if the speaker is connected to the amplifier through a capacitor, there will be positive and negative voltages appearing at the cillector of the opto-isolator.
I recommend using a small 5V relay: