I am having trouble getting the amplification of the circuit ,though I( believe it is R8/R6.Am I right?enter image description here

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    \$\begingroup\$ The 741 is a very old op and and will not work off a single rail. Look for an op amp with single supply, 5V operation. \$\endgroup\$ – user1582568 Jan 7 '16 at 18:22
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    \$\begingroup\$ The impedance of the microphone input circuit is determined by the pull up resistor and the microphone. The input resistance in effectively in series with this, so assuming the microphone is high impedance, you have 100k / (2.2k + 1k) giving a lower gain that you expected. \$\endgroup\$ – user1582568 Jan 7 '16 at 18:25
  • \$\begingroup\$ Opamp: LM358 (dual) or LM324 (quad) is cheap and available (and also old) single supply 741 alternative. \$\endgroup\$ – Russell McMahon Jan 7 '16 at 20:53

enter image description here

Recommended supply voltage is minimum 20V (+/-10V) - don't expect miracles from this aging and unhealthy device.


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