The project circuit design is a FM Bugger circuit. It works like a transmitter that transmits and projects information signals into the air wherein a FM radio will act as a receiver which would receive the transmitted signal. The circuit and the FM radio must be tuned-in with the same frequency to be able to transmit and receive information in the same channel. The FM bugger circuit is originally designed to be used like a spy gadget to eavesdrop other people’s conversations. Though it is designed that way, it is pretty much useful as a transmitter or as a walkie-talkie to relay messages in a distance [read more...]
Testing and Design Procedure
The FM bugger circuit is tested using PartSim and the NGSpice to test the output of the circuit:
FM Bugger Circuit Simulation
R1 Net1009 Mic 22K
R2 Net1009 Net1016 47K
R3 Net1003 0 33K
C1 Net1016 Mic 1NF
C2 Net1016 0 1NF
C3 Net1002 Net1003 4.7pF
C4 Net1002 Antenna 1NF
C5 Net1009 0 22NF
C6 Net1009 Net1002 50pF
L1 Net1009 Net1002 9NH
Q1 Net1002 Net1016 Net1003 2N2222
V1 Net1009 0 3V
V2 Mic 0 SINE ( 1 1 20Khz 0.0S )
R4 0 Antenna 1K
.options rshunt = 1.0e12 KEEPOPINFO
.MODEL 2N2222 NPN IS =3.0611E-14 NF =1.00124
+ BF =220 IKF=0.52 VAF=104
+ ISE=7.5E-15 NE =1.41 NR =1.005 BR =4
+ IKR=0.24 VAR=28 ISC=1.06525E-11 NC =1.3728 RB =0.13
+ RE =0.22 RC =0.12 CJC=9.12E-12 MJC=0.3508 VJC=0.4089
+ CJE=27.01E-12 TF =0.325E-9 TR =100E-9
.control
OP
write Net1002 Net1003 Net1009 Net1016 Mic Antenna I(V1) I(V2)
set appendwrite true
rusage everything
.endc
.end
The simulation of the FM bugger circuit in PartSim shows that the circuit is working. The microphone was assumed to have an input of a 20 kHz sinusoidal wave. Then, the output signal at the load, R4 assumed to be the antenna for the circuit, turns out to produce a FM signal. Therefore, the FM bugger circuit itself has a great possibility to succeed and operate in real
Project Links:
http://www.schematics.com/embed/fm-bugger-circuit-36638/
http://www.pcbweb.com/projects/DqEwZcNdcy3ddghPnJefdJIzTcWqLd
