Simple Dynamic Microphone 2 transistor Preamplifier Kit Assembled kit 9VDC Electronic Circuit : FA647 This circuit is to amplify the sound signal from the dynamic microphone which has low impedance. Dynamic mic is the microphone which is use to sing a song / Speak. Require power supply 9VDC It contains 2 transistor, some resistor and capacitor. ( not difficult to buid ) Comes with the schematic diagram PCB size : 1.6" x 1.3"