This circuit allows you to read resistors up to 20 M ohms, converting it into voltage. The circuit is from the 90s. The operational ones used admit modern equivalents.
Found in a 1965 Radio Shack documentation this oscillator can be used with modern general purpose...
In the figure we have a voltage / frequency converter circuit that can be used as a transducer interface...
This small stereo amplifier for headphones was found in a documentation on integrated circuits from...