Features: VU Meter: Stable and reliable performance. Easy to use. Driver Board: Fourth generation driver board design improves performance and precision. Compatible with Toshiba 7318 IC, enhancing drive capability and addressing limitations such as limited pointer swing and low sensitivity. Compact size for easy installation. Well-constructed and durable. Instructions: 1. Use AC or DC 12-15V power supply for transmission plate. Independent power transformer recommended, or separate winding power supply when not using backlight (45mA current). 2. L, GND, R: Low-level signal input terminals for connecting CD players, computer sound cards, preamplifiers, and other audio source devices. Connect L, GND, and R respectively for left and right channel inputs. 3. R1 and R2 are adjustable resistors on the driver board to control pointer swing amplitude. 4. Backlight requires DC 12V power; use a voltage regulator after the driver board for proper operation. 5. Ensure correct polarity when connecting interfaces. To extend backlight bulb life: 1. Reduce operating voltage to meet brightness requirements, which can significantly extend bulb lifespan. 2. Use AC power 10-12V with a 50 ohm series limiting resistor to reduce inrush current on startup. Specifications: Material: Plastic + Metal Color: Black Backlight Voltage: AC/DC 6-12V Measuring Range: 0-500μA ±10% Resistance: 650Ω ±10% Accuracy: ±5% Calibration Point: Full-scale 500μA VU Meter Size: Approx. 35 x 35 x 37mm / 1.38 x 1.38 x 1.46 inches Quantity: 1 Set Note: Please allow 1-3mm error due to manual measurement. Ensure you are comfortable with this before purchasing. Due to differences in monitor displays, actual item color may vary from the image. No retail packaging included. Package Contents: 2 x VU Meter Panel 1 x Driver Board 5 x Cable