1、Adjustable Design: This circuit board carries a microphone can also be external sound, adjust the volume potentiometer can change the volume size, adjust the adjustable inductor can change the frequency between 88‑108MHZ any frequency point. 2、Three Stages: The circuit adopts the base frequency signal, frequency doubling amplification, the last stage of high frequency amplification of three levels, open space transmitter distance is better than 100 meters. 3、Frequency Doubling Circuit: The frequency doubling circuit makes the frequency more stable and reduces the trouble of frequency variation brought by human body induction. 4、Multi Purpose: FM transmitter module kit is suitable for electronic information engineering, high frequency electronic circuit experiment and test. 5、Frequency Range: Adjusting the inductor can make the base frequency signal in 44‑54MHZ, using the nonlinearity of the transistor to produce 2x frequency signal 88‑108MHZ. Item Type: FM Transmitter Module Kit Material: PCB Adoption: Base Frequency Signal, Frequency Doubling Amplification, The Last Stage of High Frequency Amplification Suitable For: Electronic Information Engineering, High Frequency Electronic Circuit Experiments and Test Battery Specification: 2 x AA Batteries (not Included) 1 x FM Transmitter Kit 1 x Sound Cables 1 x Instruction Manual