Battery Condition Test (CB4969E)

We found this car battery status monitor circuit in an American 80s manual. The circuit has its trimpot trigger setting by driving an LED indicator.

Frequency modulator (CB4106E)
In the figure we show how to use a varicap to modulate a signal in frequency. The circuit can be...
TPS54335 2 A Stepdown Converter Synchr (COM105E)
September 2016 - Mouser Electronics already has the new TPS54335-2A from Texas Instruments...
Biquad filter LM324 (CB4005E)
We found this filter in the 1990 Motorola Linear Databook, but it can be implemented with other...