Balanced Modulator MC1556G (CB14559E)

We found this circuit in Motorola's Linear Databook in 1990. The semiconductor component used is no longer common today.

Beat Frequency Indicator (CB4889E)
This TTL circuit for digital signals up to a few dozen megahertz was found in old documentation, but...
CB24842E Variable oscillator LF381 ()
This circuit with an operational amplifier was found in the magazine Radio Electronics of...
Zero Crossing Detector (CB4000E)
This detector is from the 1990 Motorola Dataar Databook, but can be adapted to work with more...