3D Printed Printing Plates Made Using Modern Tools

October 27, 2021 by Dave Rowntree 15 Comments

It’s widely accepted that the invention of the printing press by Gutenberg in the 15^th 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 Al Williams 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 tiny bedside clock that's packed with features.

ESP32 Clock Takes Time To Give Weather Info, Too

October 27, 2021 by Kristina Panos 9 Comments

It’s fall in the northern hemisphere, so [Mike Rankin]’s kids are back in school and have returned to consulting him every morning about the weather and what they should wear. Since he’s no meteorologist, [Mike] built a beautifully dim and diminutive clock that does all the work for him, plus much more. It glows a lovely dark orange that’s perfect for the nightstand and those early morning interrogations.

In default mode, this clock displays the time, CO2 level, room temperature, and humidity in that eye-friendly orange. But wave your hand in front of the time of flight sensor, and it goes external, displaying the low and high temperatures for the day, plus the weather conditions forecast. After a few seconds of that, it goes back to default mode. The ESP fetches the time from an NTP server, then gets the weather from the OpenWeather API. The indoor weather comes from a combination sensor on the board.

Inside this tiny package is a beautifully-spun board with an ESP32 Pico D4 for a brain. In addition to the climate sensors there is a combination CO2/TVOC sensor (that’s total volatile organic compounds) to sniff out danger. There is also a pair of push buttons on the back and an ambient light sensor, but [Mike] isn’t using those just yet. Add in the Qwiic connector for future doo-dads, and you have quite the little gadget. Although the pictures make it look kind of big, you can see exactly how small it is in the demo video after the break.

[Mike] seems to like things tiny, and we admire that in a big way. Check out his positively Lilliputian ESP32 dev board.

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A troublesome Triple-Z80 arcade board requires negative voltage for audio output

Vintage Arcade Used Negative Voltage To Turn Volume Up To 11

October 27, 2021 by Ryan Flowers 50 Comments

When [Nicole Express] got her hands on the logic board for the 1986 SNK arcade game Athena, she ran into a rather thorny problem: The board expected to be fed negative five volts! [Nicole]’s analysis of the problem and a brilliant solution are outlined in her well written blog post.

[Nicole]’s first task was to find out which devices need negative voltage. She found that the negative five volts was being fed through a capacitor to the ground pins on the Mitsubishi M151516L, an obscure 12 W audio amplifier. After finding the data sheet, she realized something strange: the amp didn’t call for negative voltage at all! A mystery was afoot.

To fully understand the problem, she considered a mid-1980’s arcade and its cacophony of sounds. How would a manufacturer make their arcade game stand out? By making it louder, obviously! And how did they make their game louder than the rest?

The answer lays in the requirement for negative five volts. The amplifier is still powered with a standard 12 V supply on its VCC pin. But with ground put at -5 V, the voltage potential is increased from 12 V to 17 V without overpowering the chip. The result is a louder game to draw more players and their fresh stacks of quarters.

How was [Nicole Express] to solve the problem? ATX PSU’s stopped providing -5 V after the ISA slot disappeared from PC’s, so that wouldn’t work. She could have purchased an expensive arcade style PSU, but that’s not her style. Instead, she employed a wonderful little hack: a charge pump circuit. A charge pump works by applying positive voltage to a capacitor. Then the capacitor is quickly disconnected from power, and the input and ground are flipped, an equal but negative voltage is found on its opposite plate. If this is done with a high enough frequency, a steady -5 V voltage can be had from a +5 V input. [Nicole Express] found a voltage inverter IC (ICL7660) made just for the purpose and put it to work.

The IC doesn’t supply enough power to get 12 W out of the amplifier, and so the resulting signal is fed into an external amplifier. Now [Nicole]’s arcade game has sound and she can play Athena from the original arcade board, 1986 style!

Arcades are few and far between these days, but that doesn’t mean you can’t introduce your young ones to the joys of dropping a quarter or two, or build a gorgeous oak Super Mario Bros cabinet complete with pixel art inlays. Do you have a favorite hack to share? Be sure let us know via the Tip Line!

Add Mycelium To Your Mesh Networks

October 26, 2021 by Bryan Cockfield 21 Comments

In many parts of the world, days after a good rainfall, it’s fairly common to see various species of mushrooms popping up out of the ground. These mysterious organisms aren’t the whole story, though. The living being is a vast network of hidden fibers, called mycelium, spreading through the ground and into any other organic material it can colonize. Its air of mystery and its vast reach are the inspiration for entire Star Trek shows and, of course, projects like this LoRa-based mesh network called Mycelium.

Mycelium is the invention of [Catamine] and includes many novel features compared to more typical mesh networks. For one, it is intended to be used in low power applications to give users the ability to send messages over a distributed network rather than a centralized network like a cell phone service provider. For another, the messages are able to be encrypted and authenticated, which is not currently possible with other mesh networks such as APRS. The idea is that a large network of people with nothing more complicated than an ESP32, an antenna, and this software would be able to communicate securely in situations where a centralized network is not available, whether that is from something like a natural disaster or from a governmental organization disabling the Internet during a political upheval.

The mesh network is currently in active development, and while messages can not yet be sent, the network is able to recognize nodes and maintain a keybase. There are certainly plenty of instances where something like this would be useful as we’ve seen before from other (non-encrypted) LoRa-based network solutions which are built around similar principles.

Thanks to [dearuserhron] for the tip!

Simple Electronic Hacks Inspire Doing More With Less

October 26, 2021 by Ryan Flowers 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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There’s Not A Cassingle Thing Missing From This Cassette Deck Masterclass

October 26, 2021 by Kristina Panos 78 Comments

For [ke4mcl], this whole cassette craze of late is not a new discovery so much as it is a personal nostalgia machine. Since [ke4mcl] sees a lot of basic questions go unanswered, they made an incredible beginner’s guide to all things cassette deck. This concise wealth of information covers everything from terminology to operation, basic maintenance like repairing the belt and lubricating the motor, and appropriate cleaning methods for the various parts. Yep, we’re pretty sure this covers everything but the pencil winding technique, which you probably already knew about.

You don’t need a lot of tools and supplies to maintain a cassette deck or twelve (apparently they’re addictive) — mostly just head cleaning fluid, isopropyl, window cleaner, and a bunch of cotton swabs. And given this guide, you’ll enter the enclosure confidently, armed with knowledge about everything from the belts to the capstan to the head. This is valuable information, the kind of stuff your older brother wouldn’t take the time to explain to you in the 80s. But maybe he didn’t know reverse bias from the holes in the top of the tape.