This circuit operates with an AM radio tuned to or near 900 kHz if there is a station at this location. The coil consists of 60 + 40 turns 28 on a ferrite rod.
This circuit was found in a 1967 Raytheon manual. The transistors are from the time. Equivalent modern...
This circuit was published in a 1979 magazine, but it can still be easily assembled as the...
The circuit presented generates short pulses. This configuration was found in a publication from...