HW-810 0.28 inch Mini Digital Voltmeter Ammeter DC 100V 10A Dual 3-Digit LED Display Volt Amp Voltage Current Panel Meter Tester Features: High precision and high reliability. Reverse connection protection and does not burn. Specifications: Supply voltage: DC 4V-30.0V Current measurement range: 0-10A Voltage measurement range: 0.0V-100V Voltage error: ±1% Current error: ±2% Working current: < 20mA Refresh rate: about 620ms once Display mode: double 3-digit 0.28" LED digital tube Display color: Red + Red/ Red+ Blue Wire length: 15cm/5.91" Product size: 48x29x22mm/1.89x1.14x0.87" Mounting hole size: 46x27mm/1.81x1.06" Weight: 19g Instructions for use: 1. Before use The supply voltage of the product must be DC 4-30V. If it exceeds 30V, independent power supply is required. The current maeasurement range: 0~10A. It is best to zero before starting the measurement to make the measurement more precise and fine-tune if necessary: Power on the dual display tester normally, disconnect the load, and short-circuit the zero point briefly. The picture shown below is displayed, and the zero adjustment is successful. If the error is still large after zero adjustment, you can use a Phillips screwdriver to fine-tune the corresponding position in the above picture. Clockwise for large and counterclockwise for small. 2. Wiring method The product has two power supply modes: independent power supply and direct power supply. Note that regardless of the power supply mode, the voltage can only be DC 4V-30V. The current measurement terminal cannot be reversed. The red line is connected to the "load negative", and the black line is connected to the "power negative". The load positive and negative means the current inflow end is the load positive, the current outflow end is the load negative. 3. Common troubleshootings (1) Incorrect current display If it is directly powered or the independent power supply is co-located to ground with the equipment power supply, just  disconnect the thin black line and it can be accurate. (2) No display after being connected to power supply Any AC power that has been rectified must be filtered by an electrolytic capacitor of 1000uF or more to supply power to the meter. Notice: (1) The power supply voltage of the meter must be DC 4-30V. If it exceeds 30V, it must be independently powered according to the wiring. (2) Current detection range: 0~10A, the maximum detection current can't exceed 10A. (3) When testing the current of 10A, the wire (thick wire) can be directly soldered to the 2PIN current detecting terminal on the module. Notes: 1. There may be slight size deviations due to manual measurement, different measuring methods and tools. 2. The picture may not reflect the actual color of the item because of different photographing light, angle and display monitor. Included: 1 X Digital Voltmeter Ammeter High precision and high reliability. Reverse connection protection and does not burn.