Mini Organ (CB21653E)

This toy organ was found in Popular Electronics from January 1967. It can be constructed from modern equivalent transistors.

Stable voltmeter (CB23664E)
This sensitive two-transistor circuit was found in the June 1965 Radio Electronics magazine. The...
Vacuum Gauge (CB26175E)
This two-digit digital pressure gauge was found in the 1992 special edition of Radio Electronics...
Varicap Tuning Circuit (2) (CB13345E)
This circuit is from a 1976 technical documentation. In it we have the way of tuning a circuit using...