This is a ready breakout board with two 5V activated relays (3.3V compatible), and the signal is optoisolated, it is protected :) Easy to use and suitable for beginners, and of course students too. You can check out the tutorial by baelza.bubba in Instructables:
If you need to control AC or high current, high voltage load, this will be the perfect board.
For more information on the mini jumper function and connection, maybe this page can help:
- 5VDC two channels relay interface board
- From our tests, the control signal is 3.3V compatible, yet the VCC needs to be 5VDC. So you can use Raspberry Pi's GPIO to activate or deactivate the relay.
- Active Low configuration
- Signal Indicator LED for each Relay
- Relay Maximum Current Rating: 10A
- Relay Maximum Voltage Rating: AC 250V / DC 30V
- Can control various appliances with large current and high voltage
- Can be controlled directly by microcontrollers such as Arduino, 8051, AVR, PIC, DSP and ARM
- Build-in 2 units of Opto-Isolator IC 817C
- Instructables: Arduino 2 channels relay