Home Energy Monitor

Posted on 2022-01-28 by Nigel VH

Some friends and I recently spoke about understanding our home energy usage better, and implementing data collection for various circuits in which we had little real visibility into the actual usage and how they contributed to our energy bills.

We found an open source project making metering boards that would handle the sensing, provided with external clamp-on current transformers. Some searching, and a group bulk order later, we had a sensor board stack based on the ESP32 and a bunch of transformer cores to start working with.

We found a library for CircuitPython that had the start of what we needed, but appeared to be abandoned for some time, and needed some additional help to do everything we needed it to. After reaching out to the prior creator, we forked the repo and have been making a fair number of improvements/additions.

The new code is working well, and I have it tied into my general monitoring system, providing nice graphs. Here are some example graphs, with a longer timescale one covering several days, where we can see the heat pump usage as it works harder during the night as temperatures fall, and usage drops during the day as the temperatures come up. As well as a shorter timescale graph covering just 24 hours were we can see the individual cycles the system is running that the graphing system averages out over the longer timescale.

Posted in Electronics, Projects, Technology | Leave a comment

GPS Antenna Distribution Amplifier

Posted on 2022-01-18 by Nigel VH

In doing some recent repair and testing work on a few GPSDOs (GPS Disciplined Oscillators), I was looking to have multiple devices running at the same time without switching antennas.

There are of course generic splitters, which can be a reasonable choice in some cases, but the high frequency (1.575.42 MHz), and most GPS receivers using powered active antennas makes some traditional splitters problematic. Of course, commercial options are available targeted at GPS usage, but cost can be prohibitive, or may not have the specific combination of features you may need in your environment.

I decided to quickly throw together a design for a distribution amplifier which DC isolates all the outputs, has onboard 5V or 3.3V regulation for the powered active antenna, SAW filtering, and an amplifier to offset the losses from the four way split.

It’s a fairly simple design, with few parts, and is inexpensive to put together. I plan to 3D print a case for it and wrap the case in foil tape for some RF shielding, but it seems to be working well as is.

Now with a simplified antenna system I can feed up to four GPSDO devices for repair/testing/comparison measurements.

Posted in Electronics, Ham Radio, Projects, Technology | Leave a comment

Fully Desk Controller

Posted on 2021-09-06 by Nigel VH

Recently I picked up a second hand Fully brand sit/stand desk and modified it with a larger table top to replace my old sitting-only desk. Unfortunately it didn’t come with the memory controller, and trying to get it back to the right spot each time I switched between sitting and standing was a pain. Additionally, I wasn’t able to find any memory controllers for sale either direct or on ebay.

In some googling, I did stumble across a repo where someone had reverse engineered the pinout between the desk electronics and the controller, and this interface was the same whether the desk had the ‘dumb’ controller or the memory controller. This was an excellent resource and the starting point I needed to build my own memory controller.

I decided to experiment this time with an OLED display, and using the capacitive touch sensing functions of the ESP32, which closely mimics the factory supplied memory controller’s functionality.

There is some minor serial communications between the desk and the controller to establish that the more capable controller is being used, and for configuring some settings like height or force limits. However, most of the control happens via simple pin pulldowns in various combinations that tell the desk to store a memory, or recall a particular memory position, which made the design of the circuit board quite simple to implement.

Posted in Electronics, Random, Technology | Leave a comment

ESP32 IR Controller

Posted on 2021-05-21 by Nigel VH

I have a multi-zone ductless mini-split system installed in my house, which has been a fantastic addition and does a great job with keeping the house comfortable. Though the limitation of all zones having to be in the same mode because the compressor unit outside can only do one mode at a time.

This leaves a coordination task, as temperature set points change through the day to save energy, and mode switches move between heating and cooling as the weather changes, particularly in the spring/fall transition seasons when daytime temps could require cooling, and nights still need heat.

It’s certainly possible to manage this with the individual remotes for each zone, but it can get to be annoying to tweak all the zones a couple times a day. I decided to build a ESP32 based IR controller with a central control and schedule to ease the task.

I also took it as an opportunity to experiment with some small E-Ink displays, which are well suited to long term, low power, battery operation for the remotes.

As I was building a half dozen devices, it was a great choice for assembly with my pick and place machine I’ve written about before.

Finishing out the assembly, attaching the display and battery, and 3D printing a case for the unit wraps the project into a neat little package.

Each unit sleeps at low power using only 10uA, waking up every 15 minutes to report sensor data, check the schedule with the control system, and if scheduled send an IR command emulating the factory remotes. Overall the 2000mAh battery lasts about three months between a recharge.

The factory remote protocols were reverse engineered using my Saleae Logic analyzer, and when available docs others have written about the same or similar devices.

Posted in Electronics, Projects, Technology | Leave a comment

F150 Fuses

Posted on 2021-03-10 by Nigel VH

Recently I had to pull a friend’s trailer with my F150 pickup, and discovered the trailer had a wiring fault causing a short and blew a fuse on the trailer brake circuit. I popped open the hood to get to the fuse box up in the passenger side of the engine compartment, and found that many of the fuses are a newer style than the traditional blade or mini blade fuses.

Turns out, these new fuses are difficult to source. They weren’t available at the local auto supply, and the dealers want ridiculous prices for even a single fuse. Apparently these are a relatively new style from Littelfuse called “MCase+”. On top of that, the MCase+ comes in a slotted and unslotted variant, of which mine are the slotted variety.

I could find a small quantity of these style fuses in larger 100+ fuse variety packs sold on amazon, but a huge variety pack of fuses I’ll never use would be a waste. Fortunately I found that one of my usual electronic components suppliers has them in stock, and I could order them individually. Here’s the 20A for example. So I ordered a couple of the most common ratings I saw on my pickup to have a small set of spares without all the waste.

I’ll also note that the truck has an additional fuse block in the passenger foot well, which uses mostly more traditional mini blade fuses, though it does include some unusual three prong mini blades as well.

Posted in Electronics, Vehicles | Leave a comment