The simplest device for finding "bugs" Even if you have nothing to fear, but you would like to find out, not spying anyone behind you with listening of radio equipment, assemble the circuit shown in Fig.1.
The device is a simple detector of radio waves with audible indication. With it you can find in the room working microtransmitter. A detector of radio waves is sensitive to frequencies up to 500 MHz. To configure the detector when searching for transmitters operating by changing the length of the telescopic receiving antenna.
Telescopic antenna perceives high-frequency electromagnetic oscillations in the range up to 500 MHz, which are then detected by the diode VD1 type DB. High frequency component of the signal is then filtered by inductor L1 and capacitor C1. The low-frequency signal flows through the resistor R1 to the base of transistor VT1 KT315 type, which leads to the opening of the latter and, consequently, to the opening of the transistor VT2 type KT361. The resistor R4 appears positive voltage close to the supply voltage, which is perceived logic element DD1.1 DD1 chip type CLA as the level of logical units. This enables the pulse generator on the elements DD1.1,DD1.2, and R5 NW. With its output pulses with a frequency of 2 kHz is input to the buffer stage on the elements DD1.3, DD1.4. The load of this stage serves piezoceramic sound Converter ZQ1 type SN-1, which converts the electrical oscillations of a frequency of 2 kHz in acoustic. To increase audio volume Converter ZQ1 included between the entrance and exit of the element DD1.4 DD1 chip. It feeds the detector from the source voltage through 9 In parametric stabilizer elements VD2, R6.
The detector used type resistors MLT-0,125. The VD1 diode can be replaced by HD or any high-frequency germanium. Transistors VT1 and VT2 can be replaced by KT3102 and CT respectively. Zener diode VD2 can be any voltage stabilization 4,7-7,0 V. Piezoceramic transducer ZQ1 can be replaced by SN-22. The inductance L1 - 1 millihenry.
To configure the detector works best using a high-frequency generator. Connect to the output of the generator insulated wire antenna, and parallel to it, place the antenna of the detector. So you weakly connects the detector to the generator. Explore the entire radio band, since the frequency of 500 kHz and to the point where the detector will cease to perceive radio waves. Notice how with changing frequency, changing the sensitivity of the detector.
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