This transistorized siren was found in the patent section of Radio Electronics magazine from March 1968. The circuit uses components from the time and has a very elaborate configuration.
This interesting control circuit was found in an Electronics Now from 1988. Through it we can...
This circuit causes neon lamps to flash randomly from a low voltage supply (1.5 to 3 V). The...
Any operational amplifier, like the 741, can be used on this oscillator whose frequency depends on R1...