Programmable thermostat (CB22136E)

This circuit was found in old English documentation. The sensor is a 1M NTC. The circuit has several trigger levels for key-selected programming.

Crystal variable oscillator (CB9506E)
Found in Radio Electronics from the 90s, this circuit can vary the frequency in small values...
4046 Two-Phase VCO (CB25757E)
This circuit was found in the August 1994 issue of Electronics Now magazine. The 4046 is uncommon...
FM Tuning Indicator (CB16808E)
This circuit is based on an operational amplifier that is no longer common today but can be...