This circuit was found in an article in Radio Electronics magazine. The issue is from July 1992 and the circuit uses components that are common today.
This circuit was obtained from an old American documentation having a limited adjustment range....
This 555 timed touch switch was found in a 90s Hands-On Electronics. It triggers a buzzer, but a...
The transistors of this old circuit from the 60s can be the BC548, in a current version. The...