ITEM NAME:LM386 Electret Microphone Power Amplifier Board Gain 200 Times DC 3.7V-12V Pi TE Description: Using LM386 amplifier chip, magnification of 200 times, you can directly drive small power speakers, suitable for electret microphone amplification. Practical application: Deafness hearing aids: board connected to the microphone, power, headphones, is a good deaf hearing aids. Operating Voltage: DC 3.7V-12V Board Size(approx): 25mm x 25mm Packing List:.1pcs x LM386 Electret Microphone Power Amplifier Board. Deafness hearing aids: board connected to the microphone, power, headphones, is a good deaf hearing aids. Board Size(approx): 25mm x 25mm.