DC 12V Type B USB 8 Channel Controlled Relay Module Board Programmable Computer Control for Automation Robotics$$Electrical

When the board is connected to the PC and the PC is restarted, the relays will be toggled several times. This is because of the structure of the FTDI chip The device must be supplied with 12 VDC to work Extra PCB openings for better voltage isolation Doubled high current tracks There is no against reversed voltage! If the VCC(+12V) and GND are reversed the board will be damaged