I have an old-fashioned doorbell (like this one: https://upload.wikimedia.org/wikipedia/commons/c/c1/DoorBell_001.jpg)enter image description here

Is it safe to connect it directly to a power supply (I am using a ac/dc converter) or does it need a resistor?

  • that bell looks like the spring tension and gap can be adjusted to get it to work over a range of different voltages. I had one similar to that that would run OK of 6V and louder off 12V – Jasen Jan 17 '16 at 2:25

It looks like a battery operated (DC) rather than transformer operated (AC) bell. Start off by hooking it up to a 6 V or 9 V supply for a couple of seconds and see what happens.

You don't neeed a series resistor if your supply voltage is right. The coil resistance will limit the current.

| improve this answer | |
  • Ok, thanks. The power supply I am using takes mains AC supply and transforms it to 5VDC. – OscarPi Jan 16 '16 at 12:46
  • Hook it up! If 5 V isn't enough you'll see the armature pull in a little but not hit the bell and, maybe, not break the internal contact to let it spring back out again. – Transistor Jan 16 '16 at 12:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy