Voltage: 3V Audio output: 3.5M audio jack headset PCB outline size: 45 * 30mm The hearing aid kit consists of a microphone, a front low-amplifier, a power amplifier circuit, and a headphone jack. It has the characteristics of high sound receiving sensitivity, is practical for people with hearing impairment, and is simple to produce and low in cost. This kit is also an ideal training kit for learning analog circuits.
After plugging in the earphones, there may be screams when you first turn on the power. Do not put them in your ears first. At this time, adjust the potentiometer to the position that does not scream, and then put them in your ears to adjust until the sound is clear.