This configuration appears at several points in this section, obtained from different sources. This is from American documentation. The gain is 20 and the transistor can be a BC549.
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...