Raspberry Pi Expansion Board, Power RelayOverviewThe RPi Relay Board gives your Pi the ability to control high voltage/high current devices, easily makes normal home appliances become intelligent.
RPi Relay Board Features
Supports Raspberry Pi A+/B+/2B/3BHigh quality relays, loads up to 250VAC/5A, 30VDC/5A
Photo coupling isolation, prevent interference from high voltage circuit
Onboard LEDs for indicating relays status
Relay control jumper, allows to control the relays by custom pins other than the default pins
Comes with development resources, including examples in wiring
Pi, WebioPi, shell, python, and bcm2835.

Raspberry Pi GPIO interface: for connecting Raspberry PiRelay screw terminal: for connecting target devicesRelaysPhotocoupler: PC817Relay indicatorLED on: relay NC is opened, NO is closedLED off: relay NC is closed, NO is opened Power indicatorRelay control jumper short the jumper: control the relays by default I/Os used in the example codeopen the jumper: control the relays by custom I/Os through jumper wires