Linear Ohmmeter LM11 and TL431 (CB14548E)

We found this circuit in Motorola's Linear Databook in 1990. Integrated circuits are somewhat difficult to obtain today.

Tone-controlled microphone amplifier (CB20806E)
This circuit was found in American documentation from the 1980s. The integrated circuit used is...
Phase Shift Oscillator (CB12065E)
In the figure we have the traditional configuration of a phase shift oscillator that produces a...
Battery charger with current and voltage limiter (CB9537E)
This battery charger circuit was found in ancient American documentation. The components are...