The generator is powered by a rechargeable lithium battery. When the battery voltage is low, the low voltage indicator light turns on. Turn off the generator and recharge the battery promptly. If the generator is not used for an extended period, charge it at least once every two months to prevent battery damage. Powered and charged via MICRO USB. Current output: Rotate the output encoder knob to the right to increase output, or to the left to decrease output. Adjust the slider position using the encoder knob to select different output increments and decrements (0.01mA, 0.1mA, 1mA, 10mA). Features: Name: Signal Generator Active Current Output: 0-22 mA (minimum output approximately 0.06 mA), load: 0-550 ohms Passive Current Output: 0-22 mA (minimum output approximately 0.06 mA), external supply at 30 V, load: 0-550 ohms Output Voltage: 0V-12V (minimum output approximately 0.05V) 24V Output Voltage: Drive current up to 35mA (must not exceed 35mA) Operating Environment: 0°C to 50°C, non-condensing Item Dimensions: 90 x 70 x 28mm / 3.54 x 2.76 x 1.10in Package Dimensions: 150 x 100 x 80mm / 5.91 x 3.94 x 3.15in Package Weight: 120g / 4.23oz