This module is the latest micro-chip FM transmitter module, made with the best PCB technology, small in size, and easy to put into thick pen barrels, , etc. The frequency emitted by this module is quite stable and can be received by any radio, especially digital radio, the effect is better. need to solder the power supply and antenna by themselves. The module local oscillator circuit adopts the local oscillator circuit of the high-frequency of a black-and-white TV. The frequency is super stable, which is not comparable to capacitor three-point oscillation circuit. The module adds an amplification isolation circuit. Through the LC filter circuit and the impedance matching circuit, the second harmonic and the third harmonic are effectively filtered out. The spectrum is very clean. Reference distance: open ground 100 meters, 10-30 meters indoor environmental obstacles (3v voltage test, increasing the voltage from the greatly increased) Purpose:High-sensitivity wireless microphone, wireless recording, wireless monitoring, remote recording, maternal and child care, patient care, etc. Due to its high sensitivity, it is not suitable for stage performances and is prone to howling. Receive way: as long as the 88-108MHz FM radio can receive, with FM feature phones. Operating frequency: 85MHZ --- 115MHZ (usually between 99-101 boot default frequency) Frequency adjustment: adjustable capacitor Output Impedance: 50 ohms Operating Voltage: DC 2V- 9V Current: 9mA (3V voltage Colour: Material:PCB note:Please check as much as possible to make sure the item is what you need. Due to different batches, there may be differences in product appearance and printed text, which not affect use Package Contents: 1 * Micro-type FM Transmitter Modul Only the above package content, other products are not included. Note: Light reflection 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.