Description
In this project i had designed a spy device for capturing and transmitting sound to a distant place. In the receiver there is also a circuit for recording.
Circuit showing a fm transmitter.Here i have used a bc494 high frequency transistor for making this circuit .The fm modulator is changing the frequency of carrier signal according to the strength of information signal
In this project i had designed a spy device for capturing and transmitting sound to a distant place. In the receiver there is also a circuit for recording.
Sound Transmitting Section
The transmitter consisting of an audio amplifier .
The 741 operational amplifier is used as a pre-amplifier whose gain is
controlled by its feedback resistor R2. The 386 is a
general-purpose power amplifier used as the output driver for delivering
power to the transmitter. The gain to the transmitter may be controlled
via resistor R3. A 0.1 μF bypass capacitor must be placed across
the power supply to reduce the noise. The value of R2 must be
chosen well to prevent oscillation or distortion.
Circuit showing a fm transmitter.Here i have used a bc494 high frequency transistor for making this circuit .The fm modulator is changing the frequency of carrier signal according to the strength of information signal
Sound Receiving and Recording Section
Circuit showing a fm radio receiver .Here i have used ic cxa1619bs for making this circuit.Construct this circuit on a good pcb and give me your comment.
The voice or sound recorder built with ISD1012, ISD1016 and ISD1020 which
are produced by ISD and allow sound voice recording and play-back. The
last 2 digits show the maximum legth of recording time in seconds. This
circuits contains a non-volatile memory which can memorise sound or
voice without power supply up to 10 years. The circuit contains a
microphone amplifier and a speaker amplifier. We can say it’s a digital
voice recorder.
S1 switch is for recording / play-back ( recording in ON position ).
When S2 is OFF the IC goes in power down mode. S3 starts the recording
or play-back and must be a push-button.
Tags: wireless sound recorder, wireless spy circuits, spy sound recorder, wireless sound recording techniques
Tags: wireless sound recorder, wireless spy circuits, spy sound recorder, wireless sound recording techniques
1 comments:
Excellent post !
Sound recorder its a really good method to keep eye on our kids. thanks
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