Ultra-small volume dynamic microphone preamplifier board, two-channel design, suitable for a single lithium battery-powered, using AD828 fever op amp chip, suitable for low voltage power supply (3.7-15V).Note: This microphone amplifier board without power regulator circuit, can only use the battery or linear power supply, can not use switching power supply, otherwise there will be interference.Working Voltage: DC 3.7V-15VBoard Size: 33mm x 20mm (L*W)Notice: If you only used one channel, the other channel needs to short-circuit the input with GND, To avoid interference with the signal crosstalk.