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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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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IoT flower pot monitors moisture and temperature levels.

Smart Flower Pot Build Is All About That Base

October 26, 2021 by Kristina Panos 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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Building A Water Rocket That Lands Via Parachute

October 25, 2021 by Lewin Day 6 Comments

Water rockets are plenty of fun, but they can be even more fun if you go wild with the engineering. [The Q] is one such experimenter, who built a dual-thrust water rocket that even has a parachute for landing!

The testing took place in an area strangely reminiscent of a certain operating system.

The dual-thrust concept is an interesting one, and is well explained by fellow YouTube channel [Air Command Rockets]. The basic idea is to use several chambers on the water rocket, one which provides an initial short “boost” phase of high acceleration, followed by a longer “sustain” level of acceleration from a secondary chamber.

It’s a great way to send a water rocket ever higher, but [The Q] didn’t stop there. The build was also fitted with a wind-up module from a little walking toy, colloquially referred to as a “Tomy timer” in the water rocket scene. A rubber band is wound around the timer’s output shaft, holding a door shut containing a parachute. At launch, the windup mechanism is released, and its output shaft turns, eventually releasing the parachute. The trick is setting up the timer to release the chute just after the rocket is done with its thrust phase.

It’s a neat build, and one that would serve as a great guide to those eager to start their own journey down the rabbit hole of advanced water rockets. We’ve seen similar work before, too. Video after break.

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The Longest Ever Flight Was Over 64 Days In A Cessna 172

October 25, 2021 by Lewin Day 72 Comments

Often, when we think of long-endurance flights, our first thoughts jump to military operations. Big planes with highly-trained crew will fly for long periods, using air-to-air refuelling to stay aloft for extended periods.

However, many of the longest duration flights have been undertaken as entirely civilian operations. The longest of all happened to be undertaken by that most humble of aircraft, the Cessna 172. From December 1958 to February 1959, Bob Timm and John Cook set out to make history. The duo remained aloft for a full 64 days, 22 hours and 19 minutes, setting a record that stands to this day.

A Test of Endurance

One might expect that such an effort was undertaken to push the envelope or to strike new ground in the world of aerospace engineering. However, the real truth is that Bob Timm was a slot machine mechanic and former bomber pilot who worked at the Hacienda casino in Las Vegas. Proprietor Doc Bailey was always on the hunt for promotional ideas, and Timm pitched his boss that a record attempt in a plane bearing the casino’s branding would be a good way to go. Bailey agreed, and committed $100,000 to the effort.

Modifications to prepare the aircraft for the stunt took the best part of a year. The pint-sized Cessna was fitted with a 95-gallon belly tank, paired with a electric pump that could transfer fuel to the main wing tanks as needed. Special plumbing was also added that would allow the engine oil and filters to be changed while the engine was still running.

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NE-2 neon lamp illuminated side-by-side with non-illuminated

The Humble NE-2 Neon Lamp Has A New Trick

October 24, 2021 by Dave Rowntree 45 Comments

Ah, the humble neon lamp. The familiar warm orange glow has graced the decks of many a DIY timepiece, sometimes in a purely indicating duty, and sometimes forming a memory element in place of a more conventional semiconductor device. Capable of many other tricks such as the ability to protect RF circuits from HV transients, its negative resistance operating region after it illuminates gives us usable hysteresis which can used to form a switching element and the way the pair of electrodes are arranged give it the ability to indicate whether a voltage source is AC or DC. Now, due to some recent research by [Johan Carlsson] and the team at Princeton University, the humble NE-2 tube has a new trick up its sleeve: acoustic transduction.

The idea is not new at all, with some previous attempts at using electric discharge in a gas to detect audio, going back to the early part of last century, but those attempts either used atmospheric pressure air or other non-sealed devices that exhibited quite a lot of electrical noise as well as producing noxious gases. Not ideal.

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