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In the above circuit you can replace the switch with a large value resistor if you want a simpler circuit.
Your real problem will be with the microphone. Get one that covers the frequency range you want. Most cheap microphones have wide variations with frequency.
Another thing you need is to have the microphone out on a slender boom so that reflections from the box do not set up standing waves at the microphone.
A very expensive but very accurate German made unit has sloping sides from the microphone to the box so that the sound waves that go beyond the microphone are reflected off to the sides and not back towards the microphone.
To keep the amplifier from saturating, you need another diode from the inverting input to the output of the amplifier so that it catches the negative going output.
flatulent how do you say a large value would suffice instead of the switch.... the switch is used for resetting the output of the peak detector... how do you say a large valued resistor would take of this....
It will have a slow decay of whatever time you want. Most level meters are for measuring continuously varying sounds like speech. You want to see the level change between words and not get the highest level that occurred over several minutes.
You can have a switch that select several resistor values so that you can get the peak sound over whatever time period you want.
i think the usage of a MOSFET as a variable resistance proportional to the output voltage instead of a set of switchable resistors would be more appropriate because you can use the same MOSFET as a switch too....
i search some peak detector circuit from internet..
and i found out there are plenty different type of peak detector..
may i know tat is it all the same?
Can someone suggest me which is more suitable for the sound level meter design
generally there are many different circuits for any particular application but the main idea is the trade offs... everyone selects circuits based on their need like speed, phase margin, attenuation or gain etc etc... each circuit would have its own speciality in terms of these terms like one would be the fastest, one would have linear phase etc etc.... so the selection of the apt circuit is upto your spec needs....
how i can do so that a sinbgle pulse of 50us duration to produces a deflection no more than 2dB below that produced by a pulse having a duration of 10ms and equal peak amplitude.
how i can do so that a sinbgle pulse of 50us duration to produces a deflection no more than 2dB below that produced by a pulse having a duration of 10ms and equal peak amplitude.
Second, If this is on a Sound Pressure Level Meter, I Doubt the Microphone would truly detect and reproduce a 50us signal accurately.
Cleong said:
search some peak detector circuit from internet..
and i found out there are plenty different type of peak detector..
may i know tat is it all the same?
Can someone suggest me which is more suitable for the sound level meter design.
from the circuit diagram given above..
i have no idea about the opamp 1/2 LF353.
i using mentor graphic to draw the circuit..
in mentor graphic just have op amp LF353..
the 1/2 is mean wat?
The main part of SPL meter is microphone, which is to be calibrated . If microphone characteristics are not calibrated any measurement will done in relative unknown units and with unknown bandwidth nonlinearity.
Of course above could be forgotten if just there is need to design a toy.
from the circuit diagram given above..
i have no idea about the opamp 1/2 LF353.
i using mentor graphic to draw the circuit..
in mentor graphic just have op amp LF353..
the 1/2 is mean wat?
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