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.

Proximity sensor (CB9570E)
This circuit was found in documentation from the 1980s. The circuit uses several components of the...
100 mA Current Boost LM143 (CB14271E)
The National Semiconductor LM143 integrated circuit consists of a high voltage operational...
Music synthesizer (CB10116E)
Found in a 1970s documentation, this mini-organ toy circuit makes use of an integrated circuit from...