Features: VU Meter: Stable and reliable performance. Easy to use. Driver Board: Fourth generation driver board design improves performance and precision. Replaces Toshiba 7318 IC, enhancing drive capability and addressing limitations such as limited pointer swing and low sensitivity. Compact size, easy to install. Well-built and durable. Instructions: 1. Use AC or DC 12-15V power supply for the transmission plate. (Independent power transformer is recommended, or use a separate winding power supply. Backlight consumes 45mA current when active.) 2. L, GND, R: Low-level signal input terminals for connecting to audio sources such as CD players, computer sound cards, preamplifiers, and other audio devices. Connect L, GND, and R to left, ground, and right channels respectively. 3. R1 and R2 are adjustable resistors on the driver board that control the amplitude of the meter needle swing. 4. The backlight requires DC 12V power; a voltage regulator is used after the driver board for stable operation. 5. Pay attention to correct polarity when connecting power and signal interfaces. To extend backlight bulb life: 1. Reduce operating voltage to meet brightness requirements, which significantly extends bulb lifespan. 2. Use AC power 1012V with a 10 series resistor (50 limiting resistor) to reduce inrush current and protect the filament during startup. Specifications: Material: Plastic + Metal Color: Black Backlight Voltage: AC/DC 612V Measuring Range: 0500A 10% Resistance: 650 10% Accuracy: 5% Calibration Point: Full scale 500A VU Meter Size: Approx. 35 x 35 x 37mm / 1.38 x 1.38 x 1.46 inches Quantity: 1 Set Note: Please allow 13mm error due to manual measurement. Ensure you are comfortable with this before purchasing. Due to differences in monitor displays, the image may not reflect the actual color of the item. Thank you. No retail packaging included. Package Contents: 2 x VU Meter Panels 1 x Driver Board 5 x Cables