Rail to Rail Oscillator 555 (CB9099E)

Found in an Electronic Design from the 80s, this circuit generates a 500 Hz signal and can be used as a shield

FM Signal Generator (CB3897E)
This circuit was found in documentation from the 1970s. However, it can be implemented with modern...
Microphone Micro Amplifier (CB19624E)
The operational of this amplifier can be the 741 and the resistors R1 and R3 are of 10 k. R2B is...
Shadow Relay (CB1305E)
This well-known circuit triggers a relay when light striking the phototransistor is cut off. The...