KrNews #07 15 января 1999

Железо

Ferrum! - On methods of listening.

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                FERRUM
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(C) Mr.Linker '98


   At 6 Viper Room told about one
way to protect your phone from the plays, but today I will tell 
to the contrary, ie, the method of listening. Suddenly someone

useful.

   The device is presented in Figure
a VHF-FM transmitter
broadcasting frequencies. Eats it from the telephone line has
output power of 20 mW. This device
connected to the rupture of one of the wires
telephone network.

   The schematic diagram is shown in
Fig. Resistor R1 is included in the gap
One of the wires in the telephone network. When
hook telephone in circuit current appears, which, depending
from the apparatus and the state line, is
in the range 10-35 mA. This current, flowing
through a resistor R1, is it a voltage drop of the order of 
4-25 V. The voltage reaches the diode assembly type KTS407, 
thanks to which the device can connect without polarity. The 
high-frequency part of the scheme is powered by a parametric 
stabilizer, collected on the resistor R3, zener VD3 and 
condenser type KS191 C7. Stabilizer limits the surplus

voltage supplied from the diode assembly VD1.

   The master oscillator is made on the type of transistor VT1 
KT315. Frequency modulation by changing the capacitance varicap 
VD2 type KV109A. Modulating voltage comes from the line by R2 
and C1. The first limits the level of low-frequency signal, the 
second - eliminates the penetration of dc line circuit of the 
modulator. 

   Transistor can be replaced by
KT3102, KT368. Diode assembly can be replaced by four diodes or 
KD102 KD103. Zener any of 7-10 V. The capacitor

C7 should be targeted at the voltage
greater than the zener. Coil L1
wound on the body of the capacitor C5 and
contains 7 turns of wire SEW 0, 31 mm.
The coil L2 is wound on top of the coil L1
the same wire - 2 turns.

   When you configure the capacitors C3 and C5
adjust so that in the right range signal transmission power as 
possible. 

   Range is depending on the conditions of 30-150 m.


  CLICK <V> to view the scheme, the output
of viewing modes - ed, break. Record
scheme on the disk (in view charts)
ss +4.

On materials 'spy stuff'


                         (C) Mr. Linker

                              4.12.1998