This transformerless circuit was obtained in a 1965 publication by Ferranti. The components are from that time, with emphasis on the type of engine used.
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...