This circuit is from an old American publication, using transistors of the time and operating with a 48 V power source. The load is 2.2 ohm, and the transistors must be replaced by modern equivalents.
This 555 timed touch switch was found in a 90s Hands-On Electronics. It triggers a buzzer, but a...
Found in a 90s Popular Electronics this circuit generates signals from 530 to 1600 kHz for...
Other operational amplifiers in the series, such as the MC34072, MC34074, MC35071, MC35072,...