Position: Index > Phone Circuit >

Introduce the principle of FM Telephone Bug

2016-02-12 09:55  
Declaration:We aim to transmit more information by carrying articles . We will delete it soon, if we are involved in the problems of article content ,copyright or other problems.

This article is Introduce the principle of FM Telephone Bug. The  circuit  is simple but effective. For you to better grasp the principle, the proposed combination of text to read the schematic. This is a simple transmitter, when connected to a telephone line will be sent on this matter (execpt the dial tone) any FM radio. Frequency is adjustable from 88 years to 94 mhz and the range is 200 feet. Figure:
1. L1 is 7 22 AWG wire on a 9/64 drill bit. You may need to experiment with the number of turns.
2. Tension and compression rolls L1, you can change the frequency of the transmitter. Minimum frequency is about 88 Mhz, while Max frequency is around 94 Mhz.
3. The green line from the telephone line to IN1. The red line from the telephone line to IN2. Green line from OUT1 to call (s), as well as the red line from OUT2.
4. Antenna is a thin (22 AWG) wire about 5 inches long.
5. All capacitors are rated at 250 v or greater.
6. Is the use of telephone lines and the only use of mobile phones. S1 may be used to put the transmitter off if it is not needed.
7. If you have a problem cause burning, and then add a 300 ohm 1/4W resistor in series with it. 

 

This is the schematic of the phone transmitter

PartTotal Qty.DescriptionSubstitutions
R11180 Ohm 1/4 W Resistor 
R2112K 1/4 W Resistor 
C11330pF Capacitor 
C2112pF Capacitor 
C31471pF Capacitor 
C4122pF Capacitor 
Q112SA933 Transistor 
D1, D2, D3, D441SS119 Silicon Diode 
D51Red LED 
S11SPDT Switch 
L11Tuning Coil 
MISC1Wire, Circuit Board 

 

 

 


Reprinted Url Of This Article:
http://circuits.radio-electronics.co/radio-rf-wireless/fm-telephone-bug/