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.
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!
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.