Single Channel 5V Relay Module Expansion Board Circuit.5V Relay Board Single Channel Board is use for interfacing with Arduino,8051,AVR,PIC ARM,Raspberry Pi & All Microcotrollers Development Kit.5V Relay circuit is also use to Control Switch in Home,office,Industrial Automation IoT(Internet of Things) Research & Development,DIY Student Project Hobby R&D.Mostly 5V Relay is used for controlling higher current loads from your Digital, Microcontroller,PC parallel port or Arduino Uno etc. This board has 1 on-board relay which can switch up to 5 Amps.elays terminals (C, NC, NO) are accessible through screw terminals which makes wiring up the board very easy.There is free-wheeling diode which will further protect your micro controller from relay kick back & Reverse Supply protection included for Accidental supply reverse connection.NOTE: Color of Relay may change as per availability(White, Blue, and Black).For Example Code of 8051 Microcontroller Please Contact US: mytechnocare.info@gmail.com