In the amateur literature frequent audio amplifier circuit, which are successfully used by people from hearing loss, as a hearing aid. Most of these devices are based on ASIC. A drawback of such schemes is the large size and large power consumption. They consume about 100 mA, sometimes many times more.
Offering simple circuit hearing aid on three transistors. To power the device must be powered by a single 1.5V battery.
The list of radio:
R2 – 120 k, 0,125 W
R3 – 180 k, 0,125 W
R4 – 10 k, 0,125 W
R5 – 4.7 ohm, 0,125 W
Q1, Q2 – 2N2222, NPN structure
Q3 – 2N3906, PNP structure
C1 – 2.2uF, electrolytic capacitor
C2 – 4.7uF, electrolytic capacitor
Mic – electret microphone
Spk – headphone impedance 8-32 ohm
Bat – 1.5AT
After properly assembling device starts immediately after the.