Function: 1. The transmission frequency of the audio transmitter module can be adjusted, covering the national standard FM band of 88-108MHz. 2. The green component is an adjustable capacitor; changing it will alter the transmission frequency. 3. Features a wide working voltage range of 0.7V-9V, offering a long transmission distance and strong practicality. 4. You can use radios and mobile phones as receivers (mobile phone headphone cables have poor antenna sensitivity and are not recommended). 5. Widely used in audio transmission microphones, sleep monitoring, and other situations where sound needs to be captured. Specification: Item Type: Audio Transmitter Module Material: PCB Application: Widely used in audio transmission microphones, sleep monitoring of the elderly and children, etc., where sound needs to be captured. Frequency Adjustment Range: Wider than 88-108MHz Transmission Distance: When working at 9V, using a 70cm wire as an antenna, the transmission distance is approximately 50-100 meters in an open area, depending on the actual environment. Working Voltage | Power Supply | Transmission Power 9V | 24mA | 10.2 dBm (approx. 11mW) 8V | 21mA | 9.5dBm 7V | 19mA | 8.5dBm 6V | 17mA | 7.1dBm 5V | 14mA | 6.1 dBm (approx. 5mW) 4V | 12mA | 4.5dBm 3V | 9mA | 2.2dBm 2V | 6mA | -1dBm (approx. 1mW) 1.5V | 4.2mA | -4dBm (approx. 0.5mW, emission in general home environment) 1V | 2.4mA | -9dBm 0.7V | 0.9mA | -20dBm (approx. 0.01mW) Package List: 1 x Module