Clemson's national championship football team went to the White House on Monday where President Donald Trump hosted them for winning the title. Trump had a bunch of burgers ready for them: Wendy's, McDonald's and Burger King.
“Here’s a video I shot of President Trump showing off his 300 hamburgers.” Hunter Walker, White House Correspondent, Yahoo News.
Astrophotography is an expensive hobby. When assembling even a basic setup consisting of a telescope, camera, guiding equipment and mount, you can easily end up with several thousand dollars worth of gear. To reduce the monetary sting a little, [td0g] has come up with an innovative homebrew mount and guiding solution that could be assembled by almost any dedicated amateur, with the parts cost estimated around $100. The accuracy required to obtain high-quality astrophotographs is quite demanding, so we’re impressed with what he’s been able to achieve on a limited budget.
The inspiration for this design comes from an incredibly simple star tracking device known as a barn-door tracker, or Haig mount. Invented by George Haig in the 1970’s, this mount is essentially nothing more than a hinge aligned with the Earth’s axis of rotation. A threaded rod or screw, turned at a constant rate, is used to slowly open the hinge so that a mounted camera tracks the apparent motion of the heavens. As a result, long exposures can show pinpoint images of stars and sharp details of deep-sky objects, instead of curved star trails. [td0g] adapted this technique to drive a more traditional telescope mount, using barn-door-like drive screws on both the right ascension and declination axes. A pair of NEMA 17 stepper motors drive 4-mm pitch Acme threaded rods through toothed pulleys 3D printed from PETG.
Speaking of 3D-printed parts, this build is a good example of judicious use of the technology: where metal parts are warranted, metal parts are used, and printed plastic is relegated to those places where it can adequately do the job. [td0g] has placed the STL files for the printed parts on Thingiverse in case you want to replicate the drive.
The non-linear relationship between the threaded rod rotation and right ascension drive rate usually limits the length of exposure you can reasonably achieve with a barn-door tracker. To adjust for this, [td0g] created a lookup table in firmware to compensate the drive and allow longer exposures. He mentions that the drive will operate for three hours before it hits the end of the screw’s travel and needs to be reset, but if he can manage three hour exposures, his skies must be much darker than ours!
In case you’re wondering how accurate the tracking needs to be, [td0g] reminds us of the precision required to get blur-free images from a tracking mount: each pixel on his camera/telescope combination equates to only 1.5 arc-seconds, or 0.0004 degrees of rotation for the mount. Of course, maintaining such close tracking over any substantial amount of time for longer exposures quickly meets the limits of mechanical precision, especially in a DIY mount. To correct for unavoidable errors, [td0g] included a guiding camera and scope into the build. A modified web cam and 100 mm DSLR lens are piggy-backed on the mount to automatically correct for errors and keep the mount tracking with the Earth’s rotation. Images from the webcam are fed to the open-source PHD2 auto-guiding software, which detects bright stars in the webcam image and issues corrections to the stepper motor drivers to keep the images locked in-place. It apparently works pretty well, as the image of M31, the Andromeda Galaxy, shows.
Remember when a homemade cloud chamber was a science fair staple? We haven’t participated for decades, but it seemed like every year someone would put a hunk of dry ice in a fish tank, add a little alcohol, and with the lighting just right – which it never was in the gymnasium – you might be lucky enough to see a few contrails in the supersaturated vapor as the occasional stray bit of background radiation whizzed through the apparatus.
Done right, the classic cloud chamber is a great demonstration, but stocking enough dry ice to keep the fun going is a bit of a drag. That’s where this Peltier-cooled cloud chamber comes into its own. [mosivers] spares no expense at making a more permanent, turn-key cloud chamber, which is perched atop a laser-cut acrylic case. Inside that is an ATX power supply which runs a Peltier thermoelectric cooling module. Coupled with a CPU cooler, the TEC is able to drive the chamber temperature down to a chilly -42°C, with a strip of white LEDs providing the required side-lighting. The video below gives a tour of the machine and shows a few traces from a chunk of pitchblende; it’s all pretty tame until [mosivers] turns on his special modification – a high-voltage grid powered by a scrapped electronic fly swatter. That really kicks up the action, and even lets thoriated TIG welding electrodes be used as a decent source of alpha particles.
[Maarten Tromp] recently took the time to document some of the unusual and creative electronic projects he received as gifts over the years. These gadgets were created in the early 2000’s and still work flawlessly today. Two of our favorites are shown here: Hardware Tetris Unit (shown in the image above) and Heap of Electronic Parts.
Heap of Electronic Parts was a kind of hardware puzzle and certainly lives up to its name. It’s a bunch of parts soldered in a mystifying way to the backs of four old EPROMs — the chips with the little window through which UV is used to erase the contents. Assured that the unit really did have a function, [Maarten] eventually figured out that when placed in sunlight, the device ticks, buzzes, and squeals. [Jeroen] had figured out that the EPROMs could act like tiny solar cells when placed in sunlight, and together the four generate just enough power to drive an oscillator connected to a piezo speaker. It still chirps happily away, even today.
Hardware Tetris Unit was a black box intended to be plugged into a serial port. With a terminal opened using the correct serial port settings, a fully-functional Tetris game using ASCII-art graphics could be played. It was even self-powered from the serial port pins.
Inside Hardware Tetris is an AVR microcontroller with some level shifters, and the source code and schematics are available for download. 14 years later, computers no longer have hardware serial ports but [Maarten] says a USB-to-serial converter worked just fine and the device still functions perfectly.
There are a couple more devices documented on [Maarten]’s gifts page, including a Zork-inspired mini text adventure and a hardware board that does some trippy demos on an old Nokia color LCD. [Maarten]’s friend [Jeroen Domburg] (aka Sprite_tm) had a hand in creating most of the gadgets, and he’s someone whose brilliant work we have had the good fortune to feature many times in the past.
If you want to learn Morse code and you don’t have a teacher, you’d probably just head over to a website or download a phone app. Before that, you probably bought a cassette tape or a phonograph record. But how did you learn Morse if you didn’t have any of that and didn’t know anyone who could send you practice? Sure, you could listen to the radio, but in 1939 that might be difficult, especially to find people sending slow enough for you to copy.
Wireless World for August 3rd, 1939, has the answer in an article by [A. R. Knipe] on page 109. While you probably wouldn’t use it today, it is a great example of how ingenious you can be when you don’t have an Arduino and all the other accoutrements we take for granted today.
A Little Help From Your Friends
The idea was to build something so that your friend, your mom, or your little sister could be imposed upon to send code to you even though they didn’t know it. From the article:
The greatest handicap to the learning of Morse is undoubtedly the lack of a skilled operator to work the key so that proper receiving practice may be obtained.
The device contained a buzzer and a battery along with terminals for a key. Across the key though were two connections. One went to a “signal plate” made of brass or tin. This plate sat on a baseboard and above the plate were strips of wood. The other connection goes to a stylus which could be nothing more than a piece of wire wrapped up.
Under the strips of wood is a stencil made of paper or empire cloth which is — apparently — some sort of oil-treated cloth used as an insulator. The stencil has holes in it corresponding to each letter. The person sending you the practice code simply moves the stylus over the right part of the stencil using the wood strips as a guide.
Pros and Cons
Almost anyone could build something like this. You could probably use scrap wood, wire, and metal. You’d have to buy the battery and maybe the buzzer. But this would have been well within the technical capabilities of even a young person in 1939. With the proper use of screws you probably didn’t even need to solder.
Obviously, there are some limitations to this method. The speed could be spotty if you don’t do a nice steady glide across the stencil. The spacing between characters is probably going to be erratic as your accomplice searches for the next letter.
However, what a clever solution! Sure, today you could devise many other ways to have people send you Morse code or write (or download) a program to send your favorite website or RSS feed. There’s also plenty of code practice resources around. But if you didn’t have that, this would solve your problem.
Other Training Aids
This reminded us of the Omnigraph which was a common way to learn code way back in 1904 and beyond. These used a clockwork spring and a metal disk (effectively a cam) to operate contacts.
The military had a great interest in training Morse code operators at one time. They had machines that used inked paper tape like the TG-34-A in the video below. There was also the Instructograph (second video).
It is hard to remember when knowing Morse code was a hot job skill and not just a hobby. Then again, if telegraph faxing had caught on, all those operators would have been out of work even sooner. Of course, Morse might still come in handy if you get kidnapped. If you want to learn the sending part, the military film below might not be your best bet, but it is entertaining.
Have you ever considered the manufacture of candles? Not necessarily manufacturing them yourself, but how they are manufactured in a small-scale industrial setting? It’s something that has been of great concern to Michael Schuldt as he grappled with the task of automating a simple manual candle production process.
It’s not just an interesting subject, but the topic of manufacturing automation is something we can all learn from. This was the subject of his Adventures in Manufacturing Automation talk at the recent Hackaday Superconference which you’ll find below the break. Let’s dive in and see what this is all about!
How Complex Can a Simple Process Be?
The candle making process was simple enough, a hopper containing molten wax was positioned above a conveyor along which candle jars were sent, with the wax was dispensed into the jars from above. Periodically the hopper would need refilling, and all tasks were performed by an operator.
Michael’s first prototype automated the machinery with pneumatic components and attacked the whole process in software, with a MicroPython loop holding all possible functions. The problem he found with that approach was one that no doubt many engineers have grappled with: it quickly becomes unwieldy. The monolithic solution fell short on his essential criteria: that it be reliable, debuggable, repairable, and easy-to-use. In essence, the lesson is more hardware, less software.
There were some obvious simplifications, replacing excess software associated with simple tasks with hardware built for them. In the candle process for example there was no point in having a wax tank selection step in software when a simple switch would suffice. He came to the realisation that he was replicating common off the shelf control components such as timers or PID controllers, and his solution was to abandon the large software and produce a series of single function PCBs he calls control bricks. These are self contained units with their own displays and interfaces, that handle a particular task and are designed to run sequentially wired in a chain through which each passes control to the next. Think of it as a block diagram of an algorithm enacted as hardware modules.
A Block Diagram in Hardware
In this way he has created a general purpose toolkit that address the problem of simple process automation, so it’s worth looking at in greater detail. Each brick has a set of common interfaces, a chain input and an output to connect with other bricks, a sensor input where necessary, and an active output that can be used to trigger a relay or similar. The processor on each block is an ATmega328, chosen for convenience as he had a supply of them in hand.
There are many possible bricks that could be created to satisfy all possible functions, but so far he has created only the selection he required for the candle automation task. There is a process delay brick with a rotary encoder to set a time, a “while” brick that sets an output while a sensor condition is true, a process counter brick that increments its count every time the process passes through it, and a stop-start brick allowing the process to be halted and resumed. Loops can be enacted simply by connecting the output of the chain to its input, and the stop-start brick is normally the first in the chain. He makes the point that process parameters have to be entered manually every time the system is run rather than set in software, but he opines that for the relatively simple processes involved this should not be a problem.
Such a modular process automation system is not entirely new, indeed similar ideas could be found in the relay-driven ancestors of modern programmable logic controllers. But to have a readily available design so convenient for experimentation is an interesting development for our community, and Michael’s tale of discovery should provide interesting lessons for anyone with an automation task in front of them even if they don’t adopt his solution.