This timer, like the previous circuits, uses a currently uncommon integrated circuit. The time is given by capacitor C1 and R2 which has the range of values indicated in the diagram.
This voltage-controlled oscillator or VCO has rectangular and triangular signal outputs. The...
This circuit was obtained from a 1965 Radio Electronics. The semiconductors used admit modern...
This Hall sensor circuit is intended to isolate an audio signal applied through a coil. The...