The main function of this AC mains noise tester is to display the current voltage value and noise voltage value of the mains through the panel's OLED dot matrix screen. In this way, everyone can see the current state of the mains power very intuitively, and have an accurate judgment on the quality of the power supply. Input voltage: AC 85Vac - 250Vac 50/60Hz (accuracy +/- 1 VAC) Frequency range: 10KHz - 10MHz Noise range: 1mV - 1999mV Measurement accuracy: +/- 5% @ 1MHZ; +5% to -50% @ 10 KHz TO 10MHz Noise indication: 4 digits yellow and blue two-color OLED digital dot matrix display Dimensions: 132 * 91 * 41 MM Machine weight: 150g OLED screen displays noise voltage value and AC voltage value There are small speakers that can directly amplify the noise output, and judge the noise intensity and frequency by sound. Plug directly into a wall outlet (power outlet), no battery required; The speaker plays EMI sounds and amplitudes are demodulated to identify EMI sources (such as AM or shortwave radios, motors and arcs).