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.

Gain control with 741 and JFET (CB25572E)
This circuit was found in the April 1993 Electronics Now magazine. With it, it is possible to...
4-Digit Digital Multimeter (CB24735E)
We found this circuit in the February 1983 issue of Radio Electronics magazine. The 4-digit...
Selectable staircase generator (CB9341E)
This circuit was found in Philips documentation from 1967. The circuit uses components of the...