This small FM spy transmitter uses three transistors with an RF amplification stage. We found it in an Australian publication from 1991.
This circuit causes an LED to flash if the monitored voltage exceeds the value set in the pot. The...
This circuit is from a Radio Electronics magazine from August 1990. The indicator module is of a...
The modified Hartley oscillator seen in the figure can generate signals ranging from 3 MHz to 10...