This simple TTL siren was found in a 1980s Electronics Today International. The power supply is 5 V and the integrated circuit can be the 7400.
This circuit is from an American publication from the 60's. The power is on the order of 600 mW....
Other operational amplifiers series, such as the MC34072, MC34074, MC35071, MC35072, MC35074 d...
Found in a European magazine from the 90s, this circuit emits beeps that are several seconds apart to...