Simple Amplified Ear Circuit
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. Amplified Ear Circuit Diagram: Amplified Ear 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 Circuit Operation : The heart of the circuit is a constant-volume control amplifi...