Produced by TDA2822 deafness hearing aids

The hearing aid and deafness by TDA2822 dual amplifier IC with a small amount of peripheral components, and the universal machine on the market compared with the output power, voltage range, and other characteristics, the working voltage 1.8-15V, suitable for patients with mild hearing loss in, use.

Working principle:

The hearing aids electric schematic diagram shown in Figure 1.

Its working principle is simple: electret microphone connection into high-gain drain output circuit and external sound waves into electrical signals. TDA2822 composition BTL power amplifier, microphone output of audio signals are amplified and enough power to promote headphone sound. In order to reduce the coupling loss arising out of, use the transformer coupling, junior plus-C2, you can filter out part of the induction noise, secondary and RP connection to control the volume size. Another R1, C1 components decoupling circuit to prevent signal caused by power feedback; R2, C6-BTL circuit frequency compensation.

Parts list:

Audio transformer T used radio input amplifier alternative, such as self around, use the initial level, E14 cores are used the Φ = 0.06mm enameled wire around the turn of 2000.

Volume potentiometer WH135 variable resistance RP using direct welding at the printing plate. Earphone hole 2.5mm horizontal 2-socket.

The circuit as long as the correct Assembly, without debugging is working properly.

Power supply with two sections 5, battery, static operating current is 6mA.