Review on ACROBOTIC 4 Channel Arduino Raspberry ESP8266 by Ron Damndjperiod

Let me remind you first. In case you haven't noticed, these are MECHANICAL relays, not solid state relays. So the first thing I had to do was connect a 2 amp 5V power supply to the BBB, otherwise the power supply would fail when a board was connected. But with 2 amps of power, the BBB board supports two boards with 4 relays. The BBB then toggles the pins on and off during boot. So if something you have connected is sensitive, you may not want to apply voltage until the BBB completes *after* booting. Also, be prepared because the gate they use to get the last 5V needed to drive the relay coil acts like an inverter. Sending zero to /sys/class/gpio/gpioxx/value turns on the relay on the BBB. Since I created a routine to turn contacts on and one to turn contacts off, all I had to do was swap zero for one. And even though the relays are rated for 10 amps, a quick look at the board tells me I wouldn't try to draw more than maybe 5 amps at best. The only downside I've encountered is that the cable connectors are very small, so you can't even daisy-chain a 16GA cable between shared cables. So be prepared to use multiple disconnect strips and run a wire to each relay. Got a second board order and oooops - the driver ICs are rotated 90 degrees and the board is lower so it doesn't line up with the old mounting holes. Although the operation appears to be the same.