This passive loudness control was obtained in an old publication. The critical component is the tapped potentiometer that can be adapted with an external resistor network.
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...