Radio Frequency
Mobile phone sniffer - gsm telephone detector
With this mobile phone sniffer will track down mobile phones. Use this handy directional finder in situations and locations where the use of a mobile phone is forbidden. This neat unit will not only detect the presence of mobile phone activity (voice or text), it can home in on the culprit!
Apart from mobile phones this [...]
Preselector for SW receivers
The entry low capacitance of MOSFET modern, with two gates, will create negative inverse reaction through a uncoupled source resistor. Applied right this technique allows the creation of a entrance RF stage field with a relatively high dynamic range.
Radio amateur working on short wave: there is no need to tell, in the days of our [...]
VOX circuit schematic
VOX is a switch ordered by voice, often used at microphones instead of the classic switch button. The vox described here may be connected to almost any type of audio equipment which has an external speaker for coupling.
The threshold action is set with volume potentiometer of the audio amplifier which commands the [...]
