УСС-1 (Сигнал)

Two years ago, during the renovation of the facade of one of the 9-storey buildings, such an interesting light-signaling device fell into my hands. It hung at the end wall inside a triple module. Apparently, it worked in the security (or fire) alarm system.

The logo of the Signal plant and the inscription USS-1 1993 are embossed on the front cover. Inside there was a burned-out lamp in the socket, which was covered by the remnants of a broken plastic shade-light filter, an anti-tampering microswitch "MIZA 2a220V" (which, when trying to open the device's case, should open the loop circuit), two terminal blocks, a D826B VP diode (needed for the lamp, as in standby mode it burned halfway) and the "KOMP.468.784.001TU" sounder, about which I could not find absolutely anything on the Internet.
Inside the latter there was a printed circuit board with several parts, a D816G1 diode, a trimmer, and an MBGO-2 capacitor. The symmetrical arrangement of the elements resembles some kind of multivibrator. When 220V was connected, a deafening trill was heard, with a frequency of about 3200 hertz, which can be heard in a radius of about 30 meters.

It is interesting that the "USS-1" is not the only model from its series, there are many more versions of this device (with an MZ-1 call, two lamps at once, etc.). I also came across this model with a right-hand lamp arrangement.