Problem With Pre Amp Circuit

We have another 20 questions competition here. Next I expect to hear the OP claim that we're the ones who don't know what they need or that nobody listens to them.

sir how r u waqas here i attach here a link of research paper which we r implementing experimental diagram is at page 264 and testing frequencies are at 263 page now the one and only problem is that with pre amplifier for there two MICs in diagram . which i already told u that we need a highly precised pre amplifier for mic's which which listen from disturbance speaker a sine wave and mic's preamps shows there output at scope thats what we are getting at output.. now sir i actual problem is to design such type of pre amplifier for these MICs which shows an actual signal every other things are implemented this is just the problem . i alredy designed preaamp with lm386 but all in vain we get output signal of a diffrent shape although voice is amplified but signal is distorted . so plzz design a gud and simple pre amplifier for this which gives a gud output signal of same shape as of input shape.. so sir i only want a mic pre amplifier design which gives output of a gud shape sine wave which is applied thru disturbance speaker. plzzzz sir i very tense for that kindly help me in that matter .. also we have checked our mic's at ePal boared of dr. Nadeem lehrasab at ePal the mic gives a gud result i.e a signal of same applied shape and frequency but we r not allowed to use epal thats why i asking about you to help me in providing design of a gud pre amplifier. i will be very thank full to u . waiting for your reply soon. link of research paper http://deepblue.lib.umich.edu/bitstream/2027.42/57792/1/RaviARMARKOVAdaptiveTCST2000.pdf

Flat response mic pre-amplifiers are DC amplifier and mic need to be of flat response at first place.

sorry sir i can't understand plzz explain more about flat response

If you test the pre-amp separately with an attenuated input signal of a function generator, you will not include what ever non-linearities of the microphone.

.. also we have checked our mic's at ePal boared of dr. Nadeem lehrasab at ePal the mic gives a gud result i.e a signal of same applied shape and frequency but we r not allowed to use epal thats why i asking about you to help me in providing design of a gud pre amplifier

can u help me in giving such type of preamplifier design ????

Yes, I can design a microphone preamplifier. I hate to be rude but I do not think that you can fabricate or test such a design. Assuming that you are the original Anonymous Poster #1, you initially stated that you wanted an amplifier to "hear sound up to 100 Hz". You changed that to 100 Hz to 1 kHz. You haven't even identified what type of microphone you are using. You've never quantified the parameters of the amplifier gain or the amplifier's input and output impedance characteristics. I suggested that you should test your existing amplifier with a function generator to determine if your amplifier or microphone is producing the undesired distortion and you've not done that.

I cannot help people that do not take advice.

sir actually when i said about frequency upto 100Hz i.e why because amplifier which i designed initially is not listening frequencies lower than 1KHz and which also 1KHz which are listened by microphone are in square wave at output. But we r applying a sine wave of 139.6Hz of Vpp 5V. thats why i ask about frequency upto 100Hz sir . Now sir the circuit i designed as a preamplifier using lm386 having gain of 200. sir im using simple condensor MICs and Computer MICs. But sir i totally loose my confidence due to that sir i want a simple preamplifier circuit with variable gain i.e which contain a POT which varies the gain and give same shape of sinewave as which im applying at input thru the speaker . and sir im giving input signal thru the function generator . also sir all speakers and microphones are covered in an acoustic duct. sir here is the link of article which we r implementing and experimental diagram is at page 264. http://deepblue.lib.umich.edu/bitstream/2027.42/57792/1/RaviARMARKOVAdaptiveTCST2000.pdf sir i will be very thankful to u if u resolve my that problem im continously loosing my aal confidence in preamplifier though it is a small thing but i dont know why my mind get stuck off there sir plzzzzzz help me plzzz sir i will be very thank full to u i work at IAA(Institute of avionics and aeronautics ) as a lab engineer . but sir ur the only hope which will help me plzzz sir i want just simple preamplifier design which does not distort the signal shape. waiting for your reply sir ... thankx alot

It's late here and you've cited an in depth control systems IEEE paper. I will give you some assistance here but this is not going to be fast. I need time to work through the paper you referenced and your fractured English. (Please, do not take my last comment as an insult. Your English is much better than I am in your native language.) It would help if you have any waveforms of the input versus output you can post.

sir at that time i have no pictures . but its a simple sinewave from function generator of Vpp5v . we just require a sinewave at microphone preamplifier's output that shape of signal must not changed by preamplifier .

sir its impossible for me to post an output and input waveform but i know it is a simple input waveform of sinewave and at out we also need amplified sinewave.

sir im using lm386 as mic preamplifier . with gain 20 and also i checked it with gain 200 but problem is same . i request u to help me in providing simply a good mic pre amplifier design . we already designed a butterworth filter and Bzu matrix code in matlab is also written and we have our simulation in labview . so i simply needs a mic preamplifier design i u can help me in providing that i will be very thank ful to you also give me your complete introduction i will qoute it in my thesis and presentation. and we can co ordinate ni many matter because the place where i work i also branch of NI(national instruments) we have research labs of many technologies so we can coordinate with each other . plzzz as quick as u can provide me design do it . i will be very thank ful to you waiting for your reply

I have several pressing things to do the rest of this week, so I won't be able to get back to you until the earliest late this Sunday.

Wait a minute, you said your function generator is producing a 5V sine wave. An amplifier with a gain of 20 should turn that into 100V. A LM386 cannot handle 100 V for an output. Where is the function generator signal placed? How does it couple into the amplifier? Language barrier maybe the root of this problem but I certainly cannot help you if I don't understand what you're telling me.

ok thankxx alot for your cooperation

thankx for ur cooperation sir i have done it .