This circuit was found in a 1993 Electronics Hobbyst Handbook. The circuit operates in the FM range. The coil has 4 turns of 24 or 26 wire in a coreless form 0.5 cm diameter.
Found in a Motorola's 1968 documentation, this circuit operates at 16.5 kHz. The output is 5 A....
Using an integrated circuit from the time, we found this configuration in a 90s Radio Electronics....
With a touch of the sensor, the output of the 4013 changes state from high to low or vice versa. In...