You can actually make one of these out of any relay, the key is timing it to turn on and off very rapidly. Amazon actually sells one with and without a red indicator lamp. The bad thing is that by turning it on and off rapidly the high voltage from the magnetic field collapsing (the arc flash you see) is going to eat the contact up quick, and then fuse the two together eventually. A 1N4007 diode backwards (anode on +) on the coil will prevent arcing, but whether it still does the same thing I dunno I've never tried it.
Years ago I took a standard plastic housed relay and made it buzz like the one that was for my car above but you could BARELY hear it buzzing. It was so muted it would not work. The buzzer on this setup with the stamped steel lid and then with it not being tightly crimped to the base makes a nicely audible noise.
I too wondered how it worked before I did this video. I've also tried making one using a standard Bosch style relay but being encased in plastic, it buzzed but nothing like this style with the stamped steel lid.
You can actually make one of these out of any relay, the key is timing it to turn on and off very rapidly. Amazon actually sells one with and without a red indicator lamp. The bad thing is that by turning it on and off rapidly the high voltage from the magnetic field collapsing (the arc flash you see) is going to eat the contact up quick, and then fuse the two together eventually. A 1N4007 diode backwards (anode on +) on the coil will prevent arcing, but whether it still does the same thing I dunno I've never tried it.
Years ago I took a standard plastic housed relay and made it buzz like the one that was for my car above but you could BARELY hear it buzzing. It was so muted it would not work. The buzzer on this setup with the stamped steel lid and then with it not being tightly crimped to the base makes a nicely audible noise.
This is a diagram of the combination horn relay/key buzzer. live.staticflickr.com/392/18476113411_af2f9722dd_z.jpg
Always wondered how the buzzer section worked. Now I know.
I too wondered how it worked before I did this video. I've also tried making one using a standard Bosch style relay but being encased in plastic, it buzzed but nothing like this style with the stamped steel lid.