Low-Cost Hearing Aid

Pradeep G.

0
323

This hearing aid circuit offers the advantages of high sensitivity, low current consumption, low cost and light weight.

9Z5_1

Audio signals are sensed by the condenser microphone and amplified by two op-amps built around 741 ICs. The first IC 741 (IC1) is wired as a high gain preamplifier, while the second IC 741 (IC2) is used as a low-gain, medium-power amplifier to drive the earphone. A 470-kilo-ohm preset (VR1) is used to control the gain, while a 1-kilo-ohm preset (VR2) is used as the output volume controller.

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Assemble the circuit on a small general-purpose PCB and house it together with a 9V PP3 battery inside a cabinet the size of a cigarette pack.


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