Transmitters
74F13 mini bug transmitter
Take a look at this mini transmitter which can be used as a bug transmitter or for spy transmitter too. It uses a single IC 74F13, one coil, a capacitor, one trimmer, one resistor and ofcourse one electret mic. It is so easy to build and can give you a total coverage range of about [...]
Automatic volume control
The function of this automatic volume control circuit is to amplify signals without distorting its dynamic compression. The amplitude differences in the signal are levelled off and the disturbing effect vanish. With this tehnique, overcompensation in the volume is avoided. The circuit is used to automatically control the volume levels of cassette recorders, audio tape [...]
Foxhunt transmitter
This 2 meter 144 MHz transmitter is used in amateur competitions where a hidden transmitter is to be “hunted” using mostly homebrewed receivers and antennas. The featured electronic circuit is the transmitter. It radiates a high quality signal without unwanted harmonics. Transistor T1 and the crystal togheter make the oscillator that generates a 36MHz signal.
The [...]
