2-channel relay and optional Arduino Nano

thingiverse

This is a mounting bracket for the 2-channel version of those super common electro-magnetic relays that are so nicely controllable by microcontrollers like Arduino etc. In fact this bracket offers an optional side-car for an Arduino Nano. The Nano is mounted into the sidecar with hot glue, then the sidecar is screwed to the main bracket with #2 x 1/4" sheetmetal screws. The main bracket also uses #2 x 1/4" screws to attach the relay board. As usual, screw slots (sized for #6 sheetmetal screws) are spaced at 0.5cm multiples, for convenient mounting on Bud Industries back panels. We use this combo as a sleep/power controller, in conjunction with the super awesome Arduino low-power sleep library, to control a CDMA modem and various sensor electronics, all running on solar power. Every x minutes, the Arduino wakes up and Relay 1 applies power to the modem for about 45 seconds so it can "warm up" (find connection), then Relay 2 powers up the rest of the electronics, long enough to take readings and upload them to our cloud servers at http://tools.valarm.net - cool, right? Yeah, we could have ditched the whole relay board with a couple of SSRs or even transistors. But these things are SUPER CHEAP, you know? Also very reliable, can handle a ton of power, and are ready to rock out of the box.