This circuit is from an ancient American documentation. The transistors are of the time and the circuit uses a special sensor to detect the trigger point to produce spark plugs.
This antenna or booster amplifier operates with signals from the midband (MW) range up to the VHF...
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
This simple SCR relaxation oscillator was indicated by a 90s Popular Electronics. The frequency is...