Features:
1. Use advanced FM phase-locked loop modulation technology (PLL) to make the sound quality more realistic, more stable performance, and no shift in long-term operating frequency.
2. The audio dedicated low noise operational amplifier is used as the preamplifier of the microphone, with very low power consumption and minimal noise interference.
3. Power failure automatically remembers the frequency before power off
4. Using high-precision patch quartz crystal frequency stabilization, temperature, voltage change, the transmission frequency no longer drifts
5. The computer side configures the transmission frequency through the serial port, the frequency output is accurate, and the adjustable range is wide.

Product parameters:
Output power: 100mW
Audio frequency response range: 50Hz-18KHz
Transmitting frequency: permitted by the FCC 76.0MHz-108.0MHz (configure the transmitting frequency through the computer host computer)
Modulation mode: standard FM
Channel: mono
Supply voltage: DC 3.0V-5.0V
Working current: 35mA
Transmitting antenna: 75cm rod antenna (not included)
Emission distance: The FM transmitter module is connected to a 75cm standard rod antenna, and the radio is equipped with Desheng PL-660. The open cover is covered with a radius of 100 meters. (Note: The launch distance is for reference only, due to the difference in usage environment)

Instructions for use:
1.Power supply
The back of the module corresponds to the port GND, 3.7V is connected to the negative and positive terminals of the power supply (battery), and the power supply is recommended to use the battery or the transformer buck regulator. Switching power supplies without filters (such as mobile phone chargers, charging treasures, and on-off DC-DC power supplies) cannot be used. Otherwise, high-frequency interference generated by the power supply unit may affect the normal operation of this module. The normal working voltage of this module is 3.0-5.0V, and the power supply voltage should not exceed this range.
2.Antenna
The ANT port is used to connect the FM antenna. In order to transmit the FM signal better, it is recommended to connect the rod antenna with a length of 75cm, and there is no obstacle blocking near the antenna.
3. Frequency adjustment
This module needs to configure its transmission frequency point with the computer (refer to the frequency configuration method in the lower part of the details page for details).

Precautions:
1. Please confirm that the power polarity and power supply voltage are correct and then power on. If the voltage input exceeds 5V or the positive and negative poles of the power supply are reversed, the module may be permanently damaged.
2. The hand cannot touch the back component of the module during work, so as not to affect the normal operation of the module.

Frequency configuration method and steps:
1.Connection method of USB to TTL module and this module
(1) Connect the GND, RXD, TXD, and 5V ports of the USB to TTL module to the GND, TX, RX, and VCC of this module respectively.
2. Install the USB to TTL serial module driver
1. Install CH341SER-V3.3 [2012.02] .EXE in the driver folder of CH341SER-V3.3USB to serial port module
2. Pop-up point installation
3. Wait-installation is successful
(2) Connect the USB-to-serial port module and the module and insert the USB-to-serial port module into the computer, wait for the automatic installation of the driver. After the automatic installation is complete, open the device manager and check the serial number corresponding to the USB-to-TTL module
3. Install the serial port configuration tool Serial port tools V1.2, directly open the installation project in the folder and install by default.
(1) After the installation is complete, click Serial Port tools V1.2 on the desktop to open the serial port configuration tool.
(2) Select the port of our USB to TTL module, click COM6 to open the serial port, you can set the frequency of the module in the tool, enter a frequency in the frequency setting input box (before 76.0-108.0) and click single write The following shows that the writing is successful. Of course, you can not use this tool to set it. You can refer to the tool's instructions in other ways and send the AT command to have the same effect.
(3) You can also read the frequency and version of the module through this tool, and click the "Read" button to return the current frequency and version information of the module.

Modify the microphone pickup sensitivity description:
This module can change the pickup sensitivity of the microphone by modifying the negative feedback resistance of the microphone preamplifier circuit to meet the individual user's adaptation to special sensitivity requirements. The default value of the negative feedback resistor of the microphone preamplifier is 82K ohms. Increasing the sensitivity of this resistor microphone increases, and the sensitivity of the microphone is reduced.

Package Included:
1 x DIY Mini FM Wireless Microphone Transmitter Module Single Channel Board 3-5V 100mW Adjustable Sensitivity USB to TTL 80KΩ 76-108MHz All Parts soldered to the module) 
Instructions/schematic are NOT included. We don't provide technical assistance please make sure that you are familiar with the product before purchasing.