Just before the dawn of the PC era, IBM typewriters reached their technical zenith with the Wheelwriter line. A daisy-wheel printer with interchangeable print heads, memory features, and the beginnings of word processing capabilities, the Wheelwriters never got much time to shine before they were eclipsed by PCs. Wheelwriters are available dirt cheap now, and like many IBM products are very hackable, as shown by this simple Arduino interface to make a Wheelwriter into a printer.
[Chris Gregg] likes playing with typewriters – he even got an old Smith Corona to play [Leroy Anderson]’s The Typewriter – and he’s gotten pretty good with these largely obsolete but lovable electromechanical relics. Interfacing a PC to the Wheelwriter could have been as simple as scrounging up an original interface card for the machine, but those are like hen’s teeth, and besides, where’s the sport in that? So [Chris] hooked a logic analyzer to the well-labeled port that would have connected to the interface card and reverse engineered the somewhat odd serial protocol by banging on keys. The interface he came up with for the Wheelwriter is pretty simple – just a Light Blue Bean Plus and a MOSFET to drive the bus high and low for the correct amount of time. The result is what amounts to an alphanumeric printer, but with a little extra code some dot-matrix graphics are possible too.
Having spent a lot of time reverse engineering serial comms, we can appreciate the amount of work this took to accomplish. Looking to do something similar but don’t have the dough for a logic analyzer? Maybe you can free up $22 and get cracking on a similarly impressive hack.
The best thing about owning a 3D printer or CNC router may not just be what you can additively or subtractively create with it. With a little imagination you can turn your machine into a 3D scanner, and using capacitive sensors to image items turns out to be an interesting project.
[Nelson]’s scanner idea came from fiddling with some capacitive sensors at work, and with a high-resolution capacitance-to-digital sensor chip in hand, he set about building a scan head for his printer. In differential mode, the FDC2212 sensor chip uses an external LC tank circuit with two plain sensor plates set close to each other. The sensor plates form an air-dielectric variable capacitor, and the presence of an object can be detected with high sensitivity. [Nelson]’s custom sensor board and controller ride on a 3D-printed bracket and scan over the target on the printer bed. Initial results were fuzzy, but after compensating for room temperature variations and doing a little filtering on the raw data, the scans were… still pretty fuzzy. But there’s an image there, and it’s something to work with.
We have to admit that when we first saw [Ajoy Raman]’s Instructables post, we figured that he used a universal motor to generate a voltage from the anemometer. But [Ajoy]’s solution to the coaxial shafts problem is far more interesting than that. A discarded universal motor donated its rotor and bearings. The windings were stripped off the assembly leaving nothing but the commutator. 1kΩ SMD resistors were soldered across adjacent commutator sections to form a series resistance of 22kΩ with taps every 1k, allowing 0 to 2.2V to be read to the ADC of a microcontroller depending on the angle of the vane.
As clever as that is, [Ajoy] still had to pull off the coaxial part, which he did by drilling out the old motor shaft from one end to the other using just a drill press. The anemometer shaft passes through the hole in the shaft and turns a small DC motor to sense wind speed.
There might have been other ways to accomplish this, but given the constraints and the low cost of this solution, our hats are off to [Ajoy]. We’re a little concerned with that motor used for the anemometer, though. It could result in drag when used as a generator. Maybe a better solution would be a Hall-effect sensor to count rotations of a hard drive rotor.
Eagle is a household name for all Hackaday regulars. Here’s your chance to learn about upcoming features, get your ‘how do I do this in Eagle?’ questions answered, and get your wishlist items heard. Join us on Friday at 12:00 PST for a live Hack Chat about the Eagle PCB Design software.
Hosting this week’s discussion is [Matt Berggren], also known on Hackaday.io as technolomaniac. Matt is the Director of Autodesk Circuits and with Autodesk’s acquisition of Eagle last summer, the popular schematic design and PCB layout software falls under his purview. He has an extensive background in designing printed circuit boards — if you can do it in EDA software he knows how — this is an excellent opportunity to get answered the questions that have been stumping you.
Hack Chat are live community events that take place in the Hackaday.io Hacker Channel. Visit that page (make sure you are logged in) and look for the “Join this Project Button” in the upper right. Once you are part of the Hacker Channel, that button will change to “Team Messaging” which takes you to the Hack Chat.
You don’t have to wait for Friday, join Hack Chat whenever you like and see what the community is currently talking about.
Join Us Next Week Too for KiCad!
Are you more of a KiCad person than an Eagle person? You should still drop by this week to see if Matt changes your mind. But block out your calendar next week when [Wayne Stambaugh], one of the lead developers of KiCad will join us for a Hack Chat on Friday, 1/20/17.
Pulsed power is a technology that consists in accumulating energy over some period of time, then releasing it very quickly. Since power equals energy (or work) divided by time, the idea is to emit a constant amount of energy in as short a time as possible. It will only last for a fraction of a second though, but that instantaneous power has very interesting applications. With this technology, power levels of more than 300 terawatts have been obtained. Is this technology for unlimited budgets, or is this in reach of the common hacker?
Consider for example discharging a capacitor. A large 450 V, 3300 uF electrolytic capacitor discharges in about 0.1 seconds (varies a lot depending on capacitor design). Since the energy stored in it is given by 1/2 CV², which gives 334 Joules of energy, the power delivered will be 3340 watts. In fact a popular hacker project is to build large capacitor banks. Once you have the bank, and a way to charge it, you can use it to power very interesting devices such as:
Railguns in particular are subject to serious research. You may have read about the navy railgun, capable of reaching a muzzle speed of more than 4,600 mph (around Mach 6), more than any other explosive-powered gun. Power is provided by a 9-megajoule capacitor bank. The capacitors discharge on two conducting rails, generating an electromagnetic field that fires the projectile along the rails. The rail wear due to the tremendous pressures and currents, in the millions of amperes range, is still a problem to be solved.
Another device that uses capacitors for high power pulses is the Marx generator. It is a very simple circuit that allows you to charge a number of capacitors in parallel and then suddenly discharge them in series using spark gaps. Very large Marx generators have been built, for high voltage component testing and other purposes, but it’s also very easy to make a small lightning simulator in under an hour if you have some high voltage capacitors and resistors. Marx generators are in use in the Z machine, a Sandia National Labs project for fusion research, that is capable of shooting 26 million amperes in 95 nanoseconds. Temperatures of 3.7 billion kelvins have been obtained.
The Marx generator is a particular case of a pulse forming network, or PFN. Capacitors, inductors and transmission lines, or a combination of them are used for energy storage in various topologies. Then, the network is discharged into the load via a high voltage switch
such as a spark gap or a thyratron. The transmission line PFN is interesting because the capacitance of the conductors in the line is used for both transmission and energy storage. When the power supply is connected it slowly charges up the capacitance of the line through RS. When the switch is closed, a voltage equal to V/2 is applied to the load, the charge stored in the line begins to discharge through the load a current of V/2Z0 and a voltage step travels up the line toward the source.
Compulsators (a portmanteau for compensated pulsed alternator) are another way of delivering high current pulses. They convert rotational energy from a flywheel directly into electrical energy. The compulsator works in a similar way as a normal alternator, but is designed with minimal inductance windings to deliver extremely high currents in very short time periods. There is little information on compulsator design and, as far as we know, no hobbyist has ever made one. You have your homework assignment.
The explosively pumped flux compression generator, or EPFCG for short, is a device that generates a high power electromagnetic pulse using a high explosive to compress the magnetic flux. Million of amperes and tens of terawatts of power are produced by the EPFCG in a single pulse, since the device is destroyed in operation.
The three basic steps in flux compression are shown above.
An external magnetic field threads a closed ring conductor.
The ring’s diameter is reduced by the explosive. The variation of the magnetic flux induces a current in the ring, which in turn creates a new magnetic field, so that the total flux in the interior of the ring is maintained.
The external and induced magnetic fields add up so that the total magnetic flux remains constant, and a current is created in the ring.
The compression process allows the chemical energy of the explosives to be (partially) transformed into the energy of an intense magnetic field surrounded by a correspondingly large electric current. There are several designs of EPFCG’s. The figure shows the hollow tube type.
Pulsed power is also used in particle accelerators and high power lasers and the technology is rapidly evolving.
If you’re starting out, you may want to experiment with capacitor banks which are a relatively simple way of obtaining pulsed power. But if you do, take all necessary precautions. The power levels can be extremely dangerous.
A little over two years ago we posted an amazing contraption that holds a stack of paper sheets, folds them into paper planes, and launches them. There’s now a newer version — the PFM A5 v2.0. It is over a meter long, weighs about 10 kilograms, and features a mind-boggling number of gears and moving parts. Video is embedded below.
In one end travels one sheet of paper after the next. At each stage in the process the paper is folded (symmetrically) and creased by a vertical wheel to make up the keel of the finished plane before launching out the other end. Amazing, and not a jam or “PC Load Letter” error message in sight!
We covered an earlier version of this paper airplane gun back in 2014; the original was a marvel of engineering and this new version is no different.
There is very little that Dieter Michael Krone doesn’t know about paper airplanes. He has even written a comprehensive book (in German) with some excerpts on his site, along with a gallery of some of his work.
Named [Method-2], the bipedal giant towers over the engineers testing it at Korea’s Hankook Mirae Technology, where they appear to have done everything possible to make this thing look terrifyingly awesome. The first video below shows the mech with a pilot on board, putting the arms through their paces. We count at least six degrees of freedom on each arm, not including the five digits on each hand that look like they could punch through a brick wall. Later in the video we see a tethered walking test with no pilot, but we also found a webcam video that purports to be the first walk with a pilot. Either way, the 1.5-ton machine shakes the floor with every step.
This is still a development phase project, as evidenced by the fact that the mech seems to be getting its power from an umbilical. But this company has dumped a lot of money into this thing, and we’d bet they intend to capitalize on it. Once it can run untethered, though, watch out. Until then, we’ll settle for this mecha-baby costume.
In this age of patent trolls and multi-billion dollar companies that make intellectual property claims on plant genes and photographing objects against a white background, you’d be forgiven for thinking that a patent on a plain steel block would be yet another recent absurdity. But no – [Carl Edvard Johansson] got a patent for his “Gauge Block Sets for Precision Measurement” in 1901. As [AvE] shows us with a video on how gauge blocks can be “wrung” together, there’s more to these little blocks than meets the eye.
Gauge block wringing is probably nothing new to experienced machinists, but for the rest of us, it’s a pretty neat trick. To start the show, [AvE] gives us a little rundown on “Jo blocks” and what they’re good for. Basically, each block is a piece of tool steel or ceramic that’s ground and lapped to a specific length. Available in sets of various lengths, the blocks can be stacked end to end to make up a very precise measuring stick. But blocks aren’t merely placed adjacent to each other – they physically adhere to each other via their lapped surfaces after being wrung together. [AvE] demonstrates the wringing technique and offers a few ideas on how this somewhat mysterious adhesion occurs. It’s pretty fascinating stuff and puts us in the mood to get a gauge block set to try it ourselves.
It’s been a while since we’ve seen [AvE] around Hackaday – last time out he was making carbon foam from a slice of bread. Rest assured his channel has been going strong since then, with his unique blend of laughs and insight into the secret lives of tools. Definitely worth checking out, and still skookum as frig.
We see a lot of traffic on the tips line with projects that cover old ground but do so in an instructive way, giving us insight into the basics of electronics. Sure, commercial versions of this IR-controlled light dimmer have been available for decades. But seeing how one works might just help you design your Next Big Thing.
Like many electronic controls, the previous version of this hack required a connection to a neutral in addition to the hot. This version of the circuit relies on passing a small current through the light bulb the dimmer controls to avoid that extra connection. This design limits application to resistive loads like incandescent bulbs. But it’s still a cool circuit, and [Muris] goes into great detail explaining how it works.
We think the neatest bit is the power supply that actually shorts itself out to turn on the load. A PIC controls a triac connected across the supply by monitoring power line zero-crossing. The PIC controls dimming by delaying the time the triac fires, which trims the peaks off of the AC waveform. The PIC is powered by a large capacitor while the triac is conducting, preventing it from resetting until the circuit can start stealing power again. Pretty clever stuff, and a nice PCB design to boot.
Given the pace of technological and cultural change, it might be that [Muris]’ dimmer is already largely obsolete since it won’t work with CFLs or LEDs. But we can see other applications for non-switched mode transformerless power supplies. And then again, we reported on [Muris]’s original dimmer back in 2009, so the basic design has staying power.
Coming in at 125 cubic centimeters displacement, [Keith Harlow]’s fuel injected masterpiece isn’t too far from the size of some motor scooter engines. We doubt the local Vespa club would look upon it as legit mod, but we’d love to see it. [Keith]’s build log is a long series of forum posts, but from what we’ve seen it looks like every part was made by hand with the exception of the fuel injection system. Even the caps for the spark plugs were custom injection molded right in [Keith]’s shop. And it appears that no CNC was used – even those intake headers and the rotors for the supercharger were hogged out of aluminum using a manual mill. The exhaust headers alone are straight up works of art. There’s a staggering amount of work here, which begs the question: why? The answer in this case is obviously, “Because he can.”
Few builds compare to the level of craftsmanship on display here. The Clickspring skeleton clock comes to mind, but for model engine builds we’d have to point to [Keith]’s earlier 1/4-scale V8 engine. And we’ll hasten to add that as much time as [Keith] has spent building these works of mechanical art, he’s probably dedicated just as much time to documenting them and giving back to his community. We can all learn a lesson from that.
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