Wireless Spy Sound Recorder

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.

 

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