Two gears cannot be used at the same time or they will burn out Charging: The 3 holes are charged separately. Each hole is charged one by one for approximately 30 minutes. When all three holes are charged, the whole battery is fully charged. Attention to use time: Do not use for more than 10 seconds at a time. Use 3 times in a row. Use 20-30 seconds to cool the instrument. Prevent it from burning up due to high temperature Principle: The EMP generator generates a high frequency electromagnetic wave field. The energy saving lamp around the generator induces the electromagnetic waves and generates an electric current. When there is enough electricity, the bulb will light up. PS: There is no guarantee that the CFL will work. If it lights up, it proves that the meter is working. Specifications: Frequency: 150MHZ- Typical applications: Fingerprint locks, slot machines, claw cranes, game machines etc. Operating Voltage: DC 36V Antenna Mode: Built-in reinforced antenna + external HF antenna Supply Voltage: DC 36V Charging time: 1.5 hours total Charger: 110-220 VAC input Built-in rechargeable battery