Silicon transistor is a solid-state semiconductor device with functions such as detection, rectification, amplification, switching, voltage regulation, and signal modulation. The transistor acts as a variable current switch that controls the output current based on the input voltage. Unlike ordinary mechanical switches (such as Relay, switch), transistors use electrical signals to control their opening and closing, and the switching speed can be very fast, the switching speed in the laboratory can reach more than 100GHz. Mainly used in energy-saving lamps, household appliances, electronic rectifier and other aspects.