This circuit is from American documentation from the 70s. This configuration appears in this section obtained from other sources. The signal is sinusoidal determined in amplitude by D1 and D2.
This circuit is like the previous one except that it can be triggered electronically. The circuit is...
Found in 90s Radio Electronics, this audio indicator makes use of an integrated circuit that is...
Found in the October 1992 Radio Electronics magazine, this oscillator is controlled by switch S1....