Misc Hacks

4164 Articles

EMC Tutorial Puts You In The Loop

October 29, 2021 by 2 Comments

A student once asked his lab instructor why his amplifier was oscillating. After looking at it and noting the wild construction, the instructor remarked, “A better question would be why shouldn’t it oscillate?” The truth of it is, our circuits generate noise and especially if they are oscillating anyway. Distortion and nonlinearities generate harmonics and other component imperfections also contribute.

[FesZ Electronics] has a great video series about noise in switching power supplies and the latest talks about the hot loop. If you want to improve the noise performance of your next design, these videos are well worth watching. You can see the hot loop video below.

We really liked the homebrew noise probes. In addition to real-world probing. The video also observes circuit operation under simulation. Even if you don’t care about noise performance, there’s a lot of good information about basic switching power supply design here.

You can see the difference in a PCB that has a small hot loop versus a very small hot loop. Something to think about next time you are laying out a power supply board.

If you want to dive deeper into noise simulation, we have a good read on that for you. Or ditch simulation, and make your own cheap probe with an SDR dongle.

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An animated newspaper image from Harry Potter

Muggle Uses E-Paper For Daily Prophet Replica

October 29, 2021 by 12 Comments

News from the wizarding world is a little hard to come by for common muggles, but [Deep Tronix] has brought us one step closer to our magical counterparts with their electronic replica of the Daily Prophet newspaper.

Those familiar with the Harry Potter series will no doubt be familiar with the Daily Prophet. In the films, the newspaper is especially eye-catching with its spooky animated images, a reflection of the magic present throughout the wizarding world. This was achieved with post-production special effects for the films, but this fan-made front page of the Prophet brings the concept to life using e-paper technology and a few other interesting gadgets, all hidden away in a picture frame.

As mentioned, the heart of this project is the e-paper display and a Teensy microcontroller. While e-paper displays are excellent for displaying static text and simple graphics, they are usually not suitable for moving images due to suffering from a form of ‘burn in’, which can leave errant pixels on the screen. This means that e-paper technology typically has a relatively low frame rate for video. [Deep Tronix] has used a custom dithering library to somewhat mitigate this issue, and the results are impressive. Moving images are loaded from an external SD card, processed, and then displayed on the e-paper display, which is almost indistinguishable from the newspaper print that surrounds it.

The seemingly magical newspaper also has a face detection feature, which is enabled by a hidden camera and the venerable ESP32 microcontroller. This system integrates with the Teensy to record and then display the reader’s face on the e-paper display. A neat trick, which is made all the more eerie when these faces are later displayed at random.

We’ve seen Daily Prophet replicas before using more traditional display technology, however the move to an e-paper display goes a long way to improving the overall aesthetics, despite the lower frame rates. With Halloween just around the corner, you might just end up tricking a few people with this clever prop – check out all the build details here.

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Fixing A Broken Game Installer By Sheer Force Of Will

October 29, 2021 by 25 Comments

These days, we seldom purchase games on physical media. Even when buying titles from yesteryear, we usually download them from an online service. Some of these older games haven’t been properly ported to their new delivery platform, as [Slortibort] found out. Thus, it was time to dive into the game files and sort the problem out.

The game in question was the Hammers of Fate expansion pack for the base game Heroes of Might and Magic V. [Slortibort’s] partner bought it from Ubisoft, and ran the installer. However, the installer would report that it couldn’t find the original files from the base game, and fail to start.

Fixing the issue was no mean feat, requiring use of the Sexy Installshield Decompiler to dive into the guts of the installer to see what was going wrong. In the end, it came down to some registry key shenanigans, but the route of how [Slortibort] got there is well worth the read.

It’s a fine example of some of the issues around moving games to digital distribution; proper attention must be paid to do it right. Even then, there’s always the risk you’ll lose your games down the track. There are benefits, of course, but there’s always a tradeoff to be made.

3D Printed Printing Plates Made Using Modern Tools

October 27, 2021 by 15 Comments

It’s widely accepted that the invention of the printing press by Gutenberg in the 15th Century was the event that essentially enabled the development of the modern world, allowing access to knowledge beyond anything that came before, even if the Chinese got in on the bookmaking act some 500 years previously. Fast-forward a few centuries more and we’ve got the ability to design electronics from our arm chairs, we can print 3D objects from a machine on the coffee table, and 3D modeling can be done by your kids on a tablet computer. What a time to be alive! So we think it’s perfectly fine that [Kris Slyka] has gone full circle and used all these tools to make printing plates for a small press, in order to produce cards for her Etsy business.

Now before you scoff, yes she admits quite quickly that KiCAD wasn’t the best choice for designing the images to print, since she needed to do a lot of post-processing in Inkscape, she could have just dropped the first step and started in Inkscape anyway. You live and learn. Once the desired image was fully vectorised, it was popped into OpenSCAD in order to extrude it into 3D, thickening the contact to the base to improve the strength a little.

[Kris] demonstrates using the registration marks to align the front and rear side plates, and even (mostly) manages adding a second colour infill for a bit more pizzazz. The results look a little bit wonky and imperfect, exactly what you want for something supposed to be handmade. We think it’s a nice result, even if designing it in KiCAD was a bit bonkers.

For those interested in the OpenSCAD code, have a butchers at this gist. This project is not the first 3D-printed printing press we’ve covered, checkout the Hi-Bred for an example, and here’s the Open Press Project if you’re still interested.

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Tech In Plain Sight: Air Conditioning

October 27, 2021 by 41 Comments

I’m always amazed that technology can totally wipe out industries. Sure, some people make a living making horseshoes, for example, but the demand for them is way down compared to what it would have been when horses were the normal mode of transportation. But even so, people still make horseshoes. But think about the ice harvesting business. Never heard of it? Turns out, before refrigeration, there was a huge business of moving ice from where it naturally occurred to other places and storing it, usually underground with a lot of insulation. As far as I know, that business — including the neighborhood ice man — is totally gone now except for some historical exhibitions. We take refrigeration and air conditioning for granted, but it hasn’t been that long ago that ice was a luxury and your own reprieve from the heat was a fan.

Early Cooling

The story starts a little earlier than you might expect. In the 1840s, physician John Gorrie was concerned about “the evils of high temperature.” His hospital in Florida imported ice using the aforementioned ice trade and it wasn’t cheap nor was it very effective.

Undeterred, he developed a machine that used a horse, a waterwheel, steam, or wind power to drive a compressor to create ice. He got a patent in 1851 but it failed to catch on before his financial backer died. In fact, Oliver Evans had the idea in 1805 but never built a working machine. Jacob Perkins patented the first compression cooler in 1834, again with little practical use.

When U.S. President Garfield was shot, Navy engineers built a cooling box using cloths soaked in ice water to cool the president’s hospital room by 20 degrees. Since the mortally wounded president survived 80 days after the shooting, we presume he appreciated the comfort.

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A 7805 Regulator puts out 6.3 Volts

Simple Electronic Hacks Inspire Doing More With Less

October 26, 2021 by 18 Comments

It’s late at night. The solder smoke keeps getting in your tired eyes, but your project is nearly done. The main circuit is powered by your 13.8 V bench supply, but part of the circuit needs 9 V. You dig into your stash to find your last LM7809 voltage regulator, but all you have is a bunch of LM7805’s. Are you done for the night? Not if you’ve watched [0033mer]’s Simple Electronic Circuit Hacks video! You know just what to do. The ground pin of a LM7805 connects to the cathode of a TL431 programmable Zener diode pulled from an old scrapped TV. The diode is referenced to a voltage divider, and voila! Your LM7805 is now putting out a steady 9 V.

How did [0033mer] become adept at doing more with less? As he explains in the video below, his primary source of parts in The Time Before The Internet was old TV’s that were beyond repair. Using N-Channel MOSFETs to switch AC, sensing temperature changes with signal diodes, and even replacing a 555 with a blinking LED are just a few of the hacks covered in the video below the break.

We especially appreciated the simple, to-the-point presentation that inspires us to keep on hacking in the truest sense: Doing more with less! If you enjoy a good diode hack like we do, you will likely appreciate learning Diode Basics by W2AEW, or a Diode Based Radiation Detector.

Thank you [DSM] for the tip! Be sure to submit your the cool things you come across to our Tips Line!

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IoT flower pot monitors moisture and temperature levels.

Smart Flower Pot Build Is All About That Base

October 26, 2021 by 10 Comments

For some reason, it seems like most of the plant monitoring setups we see separate the plant and the monitoring system. This makes sense in a don’t-own-a-waterbed-and-a-cat kind of way, but it also doesn’t from an aestheitc standpoint. This build by [Jorge Enrique Gamboa Fuentes] sure does look nice and tidy as an all-in-one unit, and fortunately is built with obvious issues in mind. It tracks water level, soil moisture, and soil temperature with a single device — a STEMMA-connected soil sensor that does all the monitoring work.

This attractive beginner build is a Python-powered project that runs on a PyPortal Titano and has a speaker that anthropomorphizes the thing so it can berate you politely ask for water in English. But the real magic of this build is in the enclosure itself. Thankfully, it’s designed with a drip tray, but it also keeps the electronics out of the water, allowing just the tip of the sensor to get wet. You can view the vital signs directly on the device, or on a web dashboard whenever you’re away.

In the future, [Jorge] wants to experiment with GCP and Azure, connect more flower pots together, and add more sensors so that it is more autonomous. One of the major lessons learned was that you probably shouldn’t start with a succulent, because they need very little water and this will drag out your development time considerably unless you over-water it, which will kill it. Check it out after the break.

If [Jorge] wanted to go the easy route, they might stick this plant under an old Keurig that’s been converted to an automatic watering device.

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