Features 1.Manual Knob: FM transmitter pickup module uses manual knob to find the station more accurately, you need to manually input the receiving frequency carefully, such as input 88.1MHZ ,88.2MHZ, 88.3MHZ.... .108.0MHZ. 2.Long Range: FM emission mic core board using 9V power supply, 0.7m/2.3ft wire as antenna, open place transmitting distance of 50?100m/ 164.0?328.1ft, the actual communication distance varies depending on the environment, antenna location, receiver Sensitivity, etc. are different. 3.Through the Wall: FM transmitter pickup board can penetrate the wall, depending on the wall reinforced concrete structure, thickness and density, the general wall can wear 2?3 block, through the wall capacity by the specific antenna placement, battery voltage, radio sensitivity decision. 4.Battery Power Supply: FM transmitter pickup module can use common batteries, the higher the working voltage the greater the transmitting distance, the greater the battery capacity the longer the working time, the actual working time to the actual battery capacity shall prevail. 5.Parameters, Materials: FM radio transmitter module working voltage is ultra wide 0.7V to 9V; frequency adjustment range is wider than 88?108MHZ. premium PCB material, high density, safe and reliable, aging resistance. specificationItem Type: FM Transmitter Pickup Module_x000D_ Material: PCB_x000D_ Operating Voltage: Ultra Wide 0.7V to 9V_x000D_ Frequency Adjustment Range: Wider Than 88-108MHZ_x000D_ Transmitting Distance: 9V Work, Using 70cm/27.6in Wire for Antenna, Open Place Transmitting Distance of 50?100m/ 164.0?328.1ft, The Actual Depends on the Environment_x000D_ The Relationship Between Operating Voltage (Volts) and Supply Current (mA) and Transmitting Power (dBm) is as Follows:_x000D_ 9V, 24 mA, 10.2 dBm (That is, 11 mW)_x000D_ 8V, 21 mA, 9.5 dBm_x000D_ 7V, 19 mA, 8.5 dBm_x000D_ 6V, 17 mA, 7.1 dBm_x000D_ 5V, 14 mA, 6.1 dBm (Approximately 5 mW)_x000D_ 4V, 12 mA, 4.5dBm_x000D_ 3V, 9 mA, 2.2dBm_x000D_ 2V, 6 mA, -1dBm (~1 mW)_x000D_ 1.5V, 4.2 mA, -4 dBm (About 0.5 milliwatts, the general home environment is enough to transmit, green radiation is small!)_x000D_ 1V, 2.4 mA, -9 dBm_x000D_ 0.7V, 0.9 mA, -20 dBm (That is, 0.01 milliwatts) PackageList2 x_x000D_ _x000D_ FM Transmitter Pickup Module NoteIt is not recommended to use the earphone wire as the receiving antenna for the mobile phone, which has low sensitivity and large interference, and the effect is affected.