Pressing the door button of my commercial wireless door bell causes the mains-powered speaker unit in the hall to chime. Rather than buying another speaker unit I thought I'd make a simple extension myself. I'd then get an identical chime in my workshop.
With difficulty I was able to get access inside the unit and connected a couple of wires in parallel with its tiny speaker, like this:
I was playing with connecting that pair to a simple audio amp powering a newly located speaker in my workshop. That's when I quickly discovered (the hard way!) an obvious flaw in my idea. Both wires were at half mains voltage above earth. (Which is 0V/ground for most of my circuits.)
So I now propose to isolate that with a small mains transformer. One that I have to hand is a 240V to 18V, with respective DC ohm measurements of about 900 and 30 ohm respectively.
Can I now safely experiment with that?
Terry, East Grinstead, UK