Oh yeah… And here’s an interesting hack…
If you have an extra BRK piezo smoke alarm laying around somewhere, and you want to quiet it down for testing… You can do this little trick. Beware: It’s effects are permanent, and it will no longer be loud or usable as a life safety device!
There are 3 pins that go into a BRK smoke alarm’s piezo horn. Positive, negative, and feedback. I could go into a long discussion of how the feedback terminal works, but basically it acts as a tuner for the horn, so that it always hits its resonant frequency, which is earsplitting. For more info, watch this video:
Get your BRK alarm. For this example, I will be using the 83R style circuit board. Note that there are 3 posts coming down from the horn housing, connecting it to the board.
On the upper left hand side of the board is the feedback terminal (Battery terminals on the bottom).
Find a way to cut that pin off the horn. I just use a pair of wire cutters, and cut the whole plastic leg off the horn. It take some elbow grease. Make sure the pin is not touching the connection on the board.
Now, plug your battery in, and the alarm should make a mid toned buzz, not very loud at all. You have successfully done this hack! Now, you can test the alarm with smoke or flame and not have to deal with the loud noise annoying you or anybody around you.