This variable frequency (VFO) oscillator was found in a Japanese publication of 1962. Coil details (in Japanese, but can be deduced) are next to the diagram covering the 3.5 MHz band.
This is the traditional configuration for a limit comparator or window comparator, using two...
This circuit is connected to the sum key of a common calculator. Adjusted to produce a pulse per...
This circuit is from a 1980s Signetics documentation. The circuit separates the modulation signal from a...