Micro siren (CB21234E)

This circuit with the LM3909 can be powered with voltages from 3 to 5 V. We found it in a Popular Electronics from the 90s.

Driver for Shift Register (CB20750E)
This circuit was found in documentation two years 80. Transistors can be modern equivalents. Or...
2 meters preamplifier (CB20257E)
This circuit, very critical due to the frequency at which it operates, was found in an American...
Amplifier TDA2002 (CB11611E)
This stereo circuit with the 2002 integrated circuit. The power is 6 W per channel with 16 V of...