PhotonHome - AC Power IoT Homebase

Things are starting to come together. The board is routed, and I decided to use a 3-gang electrical box as the body, instead of trying to laser cut something. The only things left to figure out now is down to just a couple nuts and bolts...!

I have been working on this project for about a year at this point, and from my first PCB iteration to now I think I have finally finalized what I want this project to be about.

Implemented Functionality:

Battery Back-Up for Photon's internal RTC

4 Relays for Controlling 4 AC outlets

4 USB-A ports for powering additional Photons doing awesome things

Barrel Jack Input for variable power 5V supplies for High or Low current downstream applications

Basically final schematic

First Layout

Over the past few days, since receiving my PCB in the mail, and a new Particle Photon, I have been trying to figure out a direction.

The Photon offers WiFi connectivity, a built in Real Time Clock, and has a suite of pre-made sensors coming out now or very soon in the future.

My board lacked on board AC/DC conversion.

The next iteration will be something that will for sure be useful to many people, and from I have learned from finance the old PCB is a sunk cost, and cannot lead me astray from a very convenient pivot.

Here is the new schematic, not completely done, but its getting pretty close!

I have gotten the PCB in the mail, in addition I got the Particle Photon that I pre-ordered months ago! Now all I can think of is if I should make this thing a holder for a Photon, so it would be an open platform, which would also still use Arduino language through Particle, but is also WiFi enable too! This way the sensors would not necessarily have to be hardwired to the outlet. Lots to think about, but anything Photon will be a ways in the future.

Here is the draft for the DHT22 temp/humidity sensor board. This sensor was the original purpose for building this device. Next most important sensor to me is K-type thermocouple, as I want to make a toaster reflow oven.

I did the final adjustments to the PCB, added some GND and 5V, and got the silkscreen how I want it to look. Sent it in for a CAM file check and will be ordering it tomorrow.

I am getting so close to being able to order a PCB, does anyone have any feedback on my routing. Looking at this compared to the previous iteration I am quite happy with the progress over the last month and a half.

Shout out to @Luke Weston for setting me straight about how relays are isolation in themselves. It happened that the relays that I was previously using had a strange pinout where it would be difficult to really divide the circuit into two halfs - one AC - one DC. Found some better relays that fits my purpose better. Now on to routing!

But actually though, connectors are the worst! Originally I was thinking about using the ALWAYS-ON outlet for power input, but the cable necessary is called a "suicide cable" so I had to pivot. Now I am using a panel mount power entry connector, and I'm going back to using a single ring terminal for connecting the HOT wire to the PCB. From there a screw terminal will provide power to the ALWAYS-ON outlet, and the 4 CONTROLLABLE outlets, with the other side of that wire a crimped on ring terminal also. Hopefully this will make the building process easier in the end!

Posting up my latest schematic here, layout is underway but I would like some feedback if anybody has any? Just got initial word I may have an additional programmer to help out when the hardware is done. We have me on hardware/software, looks like I got another programmer today, and have a physical case being created too!