Dynamic compressor (CB21762E)

This circuit was found in a 1977 publication for radio amateurs. Transistors are common general-purpose types of the time.

Sound effect (CB9213E)
This sound effect circuit uses only one integrated. We found it in a 90's EDN. The effects can be...
Current indicator (CB20965E)
This bidirectional circuit was found in an American documentation from the 80's. The LEDs are...
Automotive Tachometer LM2907 (CB14296E)
We found this circuit in the National Semiconductor Linear Applications Handbook of 1994. The...