The transistor can be a BC548 and the coil has the following characteristics for 1 MHz. L1 has 80 turns of wire 28 in a ferrite rod and L2 of 30 and 40 turns.
We found this circuit in a year 2000 documentation. It must be powered by a voltage of 5 V as it...
This circuit was found in the February 1990 issue of Radio Electronics magazine. The circuit uses...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...