6 V x 5 mA regulator (CB21537E)

This 6V regulator with FET was found in an old Electronic Design. FET and transistor admit modern equivalents.

Tone-controlled microphone amplifier (CB20806E)
This circuit was found in American documentation from the 1980s. The integrated circuit used is...
Astable Timer 555 (CB20682E)
This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at...
Balanced modulator for SSB (CB7515E)
This circuit was found in documentation from the 70s. The transistors are from that time, but the...