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Tech Forum

September 2017

Door Chime Protection Circuit

I need a way to protect my hardwired door chimes from being accidentally “burnt up” when the doorbell button gets stuck.

A couple of times when the button got stuck, I was home and able to fix it before damage occurred. The last time it happened, however, nobody was home. Someone came to the door, and we arrived home to the smell of burnt electronics.
I’ve replaced the button more times then I can count. I guess the way the weather hits it — eventually — it becomes stuck. I am now on my third set of replacement chimes.

I have TWO 16 volt chimes (10VA) wired to a single button (LED lamp) on a 16V 30VA transformer. The transformer is much larger than normal to accommodate the two chimes.

I would like to protect the chimes in one of two ways:

  1) Simple protection — Inline fuse that would blow if the chimes were pulling current for more than (let's say) five seconds. I figure a “slow-blow” fuse would be ideal, but not sure on the rating.
  2) More complex protection — A “time out” circuit that would cut power to the chimes if the circuit was live for more than five seconds, self-resetting either after the button was released or after 60 seconds (chime would activate again, indicating a stuck button).

Eric D. Bailey
Cecilton, MD