Working temperature: -22%-55 degrees Celsius VU Meter Backlight voltage: AC6V-12V Pay special attention not to connect the output DC12V backlight voltage to the wrong VU meter when connecting , because the current will burn the meter 1. AC12V is the power supply. (It is recommended to use an power transformer or winding power supply! 2.L, G, R: This is the two-channel input terminal for low-level signal of the driver board, which is used to connect the audio of mobile phones, computer sound card pre-stage, and other audio source devices (the signal is the signal that the earphone can hear). L, GND, and R correspond to the left, ground, and right channels respectively Note: Can't connect to the power amplifier output Can not connect to the output of the power amplifier. Can not connect to the output of the power amplifier. Including car CD player cannot be used 3 Adjustable resistance "5K-V" is to adjust the brightness of the backlight. 4 Adjustable resistors "50K-1 and 50K-2" respectively control the beating amplitude of the pointers of VU meter 1 and VU meter 2, Colour:Photo Color Material:plastic Package Contents: 2 x VU meter 1 x Driver Board With Connect cable 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. This is a 35mm VU meters with drive boards Work for Phone ,Computer,Pre-amp, Mp3. Can't Connect to Amplifier Output. DC internal resistance: 650 ohm + -15% Calibration position: +5 Accuracy: Level 5. DC current; 500uA +-15% Backlight: LED*3 Tips: The product may be updated constantly, The Actual Product May Have Slight Differences Or Color Differences the color and appearance may be changed, please don't mind. And take a consideration before place the order if you have request for color or appearance.