pcf8574 connected to 8channel relay board controlled via i2c off a raspberry pi and libwiring
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this lets you have control over 8 high current channels using just usb power and raspberry pi + additional $22  dollars or so.

build with:

make



ch_control 5 1 - turns on channel 5

ch_control 6 0 - turns off channel 6

super simple


i2c to 8bit gpio board: http://www.amazon.com/Expansion-PCF8574-Expander-Evaluation-Development/dp/B00DUO17J6/ = $10
8 channel relay board:  http://www.amazon.com/Kootek-Channel-Module-Arduino-Raspberry/dp/B00C8O9KHA/ = $12


the jumper on the relay board should be in JD-VCC position