rosmawati
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Yes.Is that mean that I have to identify the correct type of microphone to be use with my pre-amp circuit?
Now we're getting somewhere, thank you.Ok I am using condenser mic.
What does it say about how to connect to the 9volt battery?. . . . it does state that we have to connect to the 9v battery power source.
What does it say about how to connect to the 9volt battery?
I posted a link under:Also, I can't find any data for a BC458 here, it seems to be a device intended for RF. Can you post its parameters, please?
I think the gsm module that I was going to use has already have opamp built in. I am not sure how to check the gain since the information they had given in its datasheet is too sparse. Can you give me a hint on how to identify its internal gain? by the way, I am using gsm module from Sirius Mobility. I am not hesitate to give you the datasheet since you look putting so much effort to help me on this matter.:-DI'd also like to know what gain stage is following the circuit you posted, there must be some other circuit with gain after the pre-amp. How much gain?
That is the part of your circuit which still puzzles me.It does not say anything but to hook the +9V and GND to the 9V power supply source mainly battery.
Inject an AC signal to its input then measure the AC signal firstly at the input and secondly at the output.Can you give me a hint on how to identify its internal gain?
1. Electret mic's are easy to identify, look at it's back side, you may found 2 pins/Pads one of them is connected to (aluminum) body of mic. That is ground, another is signal output. where you are suppose to put that 15K Pullup.
2.My experience shows that sometime this 15K not works well with some of the electric mics, and u need to modify that below upto 4.7K. so better keep one preset there.
3. Try biasing the transistor with 15K pullup and 10K pulldown.
How to simulate this? Is it by using software or what?Best way to get optimum values is to simulate same circuit with 100Hz to 10-20Khz sine wave of ultra low voltage.
How to tell this?matching of output stage of your amp
the transistor has been damaged, or perhaps you have got them mixed up
I use 3k.(What value of resistor did you use?)
I use e-cap 16V and its most positive end is properly connected to the positive end of microphone.Depending on the type of capacitor you are using, a reverse bias on the capacitor may be the cause of the noise. Use your meter to see which end of C1 is most positive when the microphone is connected, and reverse it if necessary.
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