3-decade VCO (CB21326E)

This circuit generates signals from 10 Hz to 10 kHz. We found it in a Popular Electronics from the 90's. The components admit equivalents.

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Timer 4001 2 (CB16316E)
An interesting timer is shown in the figure, using one of the 4 NAND gates of the integrated 4001....
High impedance window comparator (CB6091E)
General Electric suggests this circuit in a 1980s documentation. The operational of the time is...
0 to 9 V x 200 mA power supply (CB18936E)
This simple adjustable source uses a PNP transistor that can be the BD136 for even slightly higher...