High-speed buffer (CB9556E)

Found in a 1980s documentation, this circuit makes use of components from that time. Modern equivalents can be tried out.

Turntable preamplifier II (CB19173E)
This preamp version uses BC109 transistors that are older versions of the current BC549 in plastic...
Electronic Crossover (CB20648E)
This circuit separates the bass from the treble in an audio signal. The circuit is from a Hands On...
Application of the 4 and a half digit AD7129 converter (CB14869E)
This circuit is from the 1983 Intersil manual. The display is a 4.5-digit LCD, and the power...