Design a microphone preamplifier for Wireless Noise Monitoring application

I was designing a microphone pre-amplifier circuit for Wireless Noise Monitoring application.



I used an amplifier AD797AN (datasheet:http://www.kynix.com/uploadfiles/pdf/AD797AN.pdf ) which connected to a 9V power supply. The multisim simulation of the circuit with a function generator gives the expected gain of around 7.8. But the same circuit in the breadboard with the microphone gives the gain of only around 5. Please let me know what improvements are needed in the circuit to get the expected gain of 7.8?

How are you measuring the gain with the microphone in circuit?

Cheers

Ian

Sheeran said:

Please let me know what improvements are needed in the circuit to get the expected gain of 7.8?

Click to expand...

Maybe by increasing the powersupply voltage to greater than the min.required +/-5VDC for a more predictable result. At least your 9VDC (hooked up for +/-4.5VDC) is a volt short.

Microphone source impedance into R5(1K8) loads signal down?

Jakob E.

Gain of the amplifier circuit when driven from a zero ohm source impedance is (6190+910)/910 = 7,8 x.
But...the source impedance isn't zero ohms.
The microphone output impedance in combination with the 1.8K resistor produces some attenuation.
Simply increase the value of R1 to obtain the gain that you want!