[ FrikZona Journal #2 ] :: [ Телефонные жучки ] :: [ FM Telephone Bug ]


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Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet. It is extremely easy to build and is therefore a good, useful beginner project.

Принципиальная схема


Обозначение Описание
R1 180 Ом
R2 12 КОм
C1 330 пФ
C2 12 пФ
C3 471 пФ
C4 22 пФ
Q1 2SA933
D1, D2, D3, D4 1SS119
D5 Кр. светодиод
S1 Переключатель
L1 Настроечная катушка


Notes
  • L1 is 7 turns of 22 AWG wire wound on a 9/64 drill bit. You may need to experiment with the number of turns.

  • By stretching and compressing the coils of L1, you can change the frequency of the transmitter. The min frequency is about 88 Mhz, while the max frequency is around 94 Mhz.

  • The green wire from the phone line goes to IN1. The red wire from the phone line goes to IN2. The green wire from OUT1 goes to the phone(s), as well as the red wire from OUT2.

  • The antenna is a piece of thin (22 AWG) wire about 5 inches long.

  • All capacitors are rated for 250V or greater.

  • The transmitter is powered by the phone line and is on only when the phone is in use. S1 can be used to turn the transmitter off if it is not needed.

  • If you have problems with the LED burning out, then add a 300 ohm 1/4W resistor in series with it.

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