This sensor circuit for currents of the order of nanoamperes was found in an American documentation from the 1980s. The components are from that time.
The main feature of this RF oscillator that operates in the range of 100 to 800 kHz is its low...
Many people currently use the bicycle as a means of transportation and leisure in large cities....
In this radio the coil can be made with 70 + 30 turns of wire 28 to 32 in a cardboard or PVC tube...