7-segment display driver (CB20551E)

We found this circuit in English documentation from 1996 for PCs. The circuit is for common cathode display.

Variable Active Cycle Frequency Doubler (CB5027E)
This circuit was found in an Electronics World magazine from 1990. The circuit can be mounted...
Audio Amplifier LM3900 (CB13834E)
In the figure, from a documentation from the 70s, we have a few-watt amplifier for general use....
Play-Records from the 60s with the CA3020 (CB18500E)
This circuit is from 1968 and consists of an amplifier for turntable of the time. The CA3020 was...