Question

a microphone delivers 300 mv to 300ohm input of an amplifier.the ac power delivered to 8ohm speaker is 18watt.what is power gain is amplified?
please explain​

Answer 1

This circuit, connected to 32 Ohm impedance mini-earphones, can detect very remote sounds. Useful for theatre, cinema and lecture goers: every word will be clearly heard. You can also listen to your television set at a very low volume, avoiding to bother relatives and neighbors. Even if you have a faultless hearing, you may discover unexpected sounds using this device: a remote bird twittering will seem very close to you.

Circuit Diagram:

Circuit Diagram

Parts:

P1 = 22K

R1 = 10K

R2 = 1M

R3 = 4K7

R4 = 100K

R5 = 3K9

R6 = 1K5

R7 = 100K

R8 = 100R

R9 = 10K

C1 = 100nF 63V

C2 = 100nF 63V

C3 = 1µF 63V

C4 = 10µF 25V

C5 = 470µF 25V

C6 = 1µF 63V

D1 = 1N4148

Q1 = BC547

Q2 = BC547

Q3 = BC547

Q4 = BC337

J1 = Stereo 3mm. Jack socket

B1 = 1.5V Battery (AA or AAA cell etc.)

SW1 = SPST Switch (Ganged with P1)

MIC1 = Miniature electret microphone

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