01-02-2012, 12:40 PM
ELECTRONIC STETHOSCOPE
[attachment=16963]
objective:
The aim of technology is to make products in a large scale for cheaper prices and increased quality. Stethoscopes are not only useful for doctors, but for home mechanics, exterminators, spying etc. Standard stethoscope provides no amplification which reduces its use for a certain extent .But an “ELECTRONIC STETHESCOPE” uses op-amps to amplify the signal and includes a low pass filter to remove background noise.
CIRCUIT DESCRIPTION
A Stethoscope operates as a low-noise microphone
pre-amp. Its gain is only about 3.9 because of the high
output impedance of the drain of the FET inside the
electret microphone causes U1a’s effective input
resistor to be about 12.2K. C2 has a fairly high value in
order to pass very low frequency (about 20 to 30Hz)
heartbeat sounds.
THEORY:
An electronic stethoscope is used to listen to your heartbeat and you would normally use a listening tube or stethoscope. This electronic stethoscope circuit uses a piezo sounder from a musical greetings card or melody generator, as a microphone. This transducer has an output signal in the order of 100 mV and its low frequency response is governed by the input impedance of the amplifier.
ADVANTAGES:
Operation of an electronic stethoscope is very
simple and intuitive. The following are the features of
an electronic stethoscope.
.Hear chest sounds, fetal sounds, and check blood
pressure through clothing layers.
.Direct conversion of sound from the chest to
electronic signals minimizes SOUND INTERFERENCE.
.Ideal stethoscope for use in air and ambulance
transport of patients.
.Separate adjustable filter and volume controls.
[attachment=16963]
objective:
The aim of technology is to make products in a large scale for cheaper prices and increased quality. Stethoscopes are not only useful for doctors, but for home mechanics, exterminators, spying etc. Standard stethoscope provides no amplification which reduces its use for a certain extent .But an “ELECTRONIC STETHESCOPE” uses op-amps to amplify the signal and includes a low pass filter to remove background noise.
CIRCUIT DESCRIPTION
A Stethoscope operates as a low-noise microphone
pre-amp. Its gain is only about 3.9 because of the high
output impedance of the drain of the FET inside the
electret microphone causes U1a’s effective input
resistor to be about 12.2K. C2 has a fairly high value in
order to pass very low frequency (about 20 to 30Hz)
heartbeat sounds.
THEORY:
An electronic stethoscope is used to listen to your heartbeat and you would normally use a listening tube or stethoscope. This electronic stethoscope circuit uses a piezo sounder from a musical greetings card or melody generator, as a microphone. This transducer has an output signal in the order of 100 mV and its low frequency response is governed by the input impedance of the amplifier.
ADVANTAGES:
Operation of an electronic stethoscope is very
simple and intuitive. The following are the features of
an electronic stethoscope.
.Hear chest sounds, fetal sounds, and check blood
pressure through clothing layers.
.Direct conversion of sound from the chest to
electronic signals minimizes SOUND INTERFERENCE.
.Ideal stethoscope for use in air and ambulance
transport of patients.
.Separate adjustable filter and volume controls.
