The latest upgrade: LM317 low ripple voltage regulator circuit design, preamplifier were used in a fever-class op amp OP275, input bridge reactor, can be AC and DC, DC input can be divided into positive and negative, so more convenient to useDynamic microphone, electret microphone universal, a broader purposeJP1, JP2 Select the type of microphone for setting the pin: JP1, JP2 all the way, jumper plug is the working mode of the electret microphone, jumper cap plug is dynamic microphone mode of operation.Microphone reverberation chip using PT2399, microphone amplification, preamplifier respectively, using a fever class op amp OP275, microphone board two microphone volume can be independently controlled. Dynamic microphone, electret microphone can be universal. Board has MIC-1 volume, MIC-2 volume, reverberation times, reverb, external audio volume adjustment.Working voltage: AC: 6v-17v or DC: 12v-24vColour:RedMaterial:plasticSize:100x50mmPackage Contents:1 * Audio Amplifier BoardOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.