Rock Polishing

I recently came across some interesting looking assortment bags of rocks for tumbling from Dan Hurd Prospecting, and decided to pull out the old tumbler and give them a go.

The rocks arrive as rough chunks, and are loaded into the tumbler with some coarse grit, and some ceramic media.

After the coarse and medium grits are completed they have the edges all rounded off, some of the stones have broken up into some smaller pieces, and they’re shiny while wet, though when dry they still have a matte finish.

They go back in for more rounds of tumbling, now with the fine and polishing grits, and come out shiny and finished. Some of the pieces broke up a little more, but overall I’m pretty happy with the results.

Posted in Random | Leave a comment

Quick Fiber Optics Tip

I was recently having a conversation with a colleague about doing some troubleshooting on a fiber optic network connection he was working on, and was looking for a way to verify light was actually making it down the fiber.

There are of course specialized tools that will measure this, and you can also get inexpensive ‘business cards’ with a coating that lights up visibly when you shine IR on them. However, even better is something you have with you all the time. Your smartphone!

The camera in almost all smartphones is at least somewhat sensitive to IR light, so you can do a quick check using your phone. This trick also works for TV remotes if you’re not sure if the batteries are dead.

On an LC connector like this, you should expect to see light on one side, and the dark one is for the return signal from the optic you’re plugging it into.

Just be careful not to look at the laser with your remaining good eye!

Posted in Electronics, Random, Technology | Leave a comment

Dual Hose Portable Air Conditioner Mod

Many portable air conditioners are known to be problematic, and often reviled, for using a single hose to vent hot air outside. The problem with which, is that the air that gets pumped outside has to be replaced in your home, and that air is just going to come in from outside.

This cycle of pumping out hot air, and that being replaced with more hot air from outside, makes them less effective at cooling spaces, and you waste electricity running them more.

They do make two-hose models, which solve this problem by using a second hose to bring in outside air to exchange over the radiator before pumping it out again, resulting in no outside air being brought into the house.

Unfortunately these two-hose models are the significant minority, and unfortunately the impacts/benefits are nebulous. When all you know is that they’re ‘better’ but not really any information on how much better, it’s hard to justify buying a more expensive model.

I’ve had a single hose model for a few years to cool my basement office/workshop space, and have left it run as designed until now, knowing that it’s ‘less efficient’ but not putting really much thought into it. However, the wildfire smoke recently made me rethink trying to retrofit my unit into a two-hose operation, and try to reduce the amount of outside air (and pollutants) being pulled into the house.

I cut and taped a cardboard box to enclose the intake portion of the radiator, and fed in some 6″ ducting from the hardware store, which matches the ducting for the exhaust, and fed both hoses out through the window.

First impressions are that subjectively it does feel like it does a better job of cooling. I don’t feel like I have to run it as hard, or turn the set temperature down as low to get the room to where I want it. However, subjective data is easily biased, and also isn’t great for convincing others.

Fortunately I have both indoor and outdoor air quality (particulate) sensors, and the data shows a remarkable change.

We are looking at a 7 day graph window, and we can see in the Indoor graph, that for a large portion of the earlier part of the week, I have been fighting to keep air quality inside the house at a reasonable level, using box fans with filters, and occasionally running the central furnace on fan mode to pull air through the furnace filter as well.

The marked red line is where I modified the air conditioner to two-hose operation. After which we see a very significant drop off and better air quality inside the house without having to run the central furnace fan/filter. Meanwhile air quality levels outside remain well above an AQI of 100, so the improvement in indoor quality is not due to an improvement outdoors.

To me, this is pretty clear evidence just how much air this portable air conditioner was causing the house to exchange with the outdoors, and how much of an impact it can have on the efficiency of cooling the house, as well as in situations like mine where there is wildfire smoke, the air quality within the house.

Posted in Life, Random, Weather | Leave a comment

Laser Cutting a Paper Solder Paste Stencil

In the process of working on a PCB for another project, I ended up with a component that was harder to solder properly than I had originally expected, and had not ordered a solder paste stencil with the board.

I ended up thinking if I could find reasonable material, I could cut a stencil for this part using my laser cutter. Some stencils are made of kapton, but I don’t have any larger sheets of kapton, nor do I think my 10W diode laser would cut it.

I ended up finding that my standard printer paper was just about the right thickness for a stencil, at about 4 to 5 thousandths of an inch thick. I was a bit worried that the finer features between the pads might tear, but it was worth trying.

Turns out, that at least for low quantities, paper makes a pretty reasonable homebrew stencil material.

Posted in Random | Leave a comment

Customizing a Smart Plug

Recently some projects around the house have been in need of some better ‘home automation’ than a standard timer can provide, so I went looking for a smart plug that was either ‘dumb’ enough for my liking (didn’t tie you to some manufacturer’s cloud service), or was modifiable with my own code.

Fortunately the ESPHome project is a great resource both for a list of devices that are reasonably easily modifiable, and for a codebase built for running your own automation on a number of IoT devices.

I looked through their list a bit, and found a few devices that were built around the ESP32, which I am already well familiar with, and which were inexpensive and easily available to me through the usual retailers. In the end I ended up settling on the Wyze Plug Outdoor, and picked up a few units.

Internally there’s some test points that I soldered some headers on to get access to the serial UART and the power pins. After hooking that up, it’s a quick process to flash some ESPHome code on the unit, or write your own with Arduino / your IDE of choice.

So far, I’ve been really happy with these units. They seem to be built reasonably well, they aren’t glued together so they’re easy to open up and reprogram, they’re suitable for outdoor use if needed, and have two individually controllable outlets.

Posted in Electronics, Random, Technology | 1 Comment