We find this circuit in American documentation from the 1980s. It consists of a frequency folder using a varicap. The capacitors and coils depend on the frequency of operation.
Found in a 90s Popular Electronics, this circuit is intended for amplifying analog video signals....
In the figure we have an anti-ring or debouncer circuit with 555. The duration of the pulse is...
Bike speedometer (CB20497E) This circuit can be powered by a solar cell. The circuit is from a...