Repairing A Vintage Sharp MemoWriter

March 26, 2019 by Tom Nardi 9 Comments

As you may know, we’re rather big fans of building things here at Hackaday. But we’re also quite partial to repairing things which might otherwise end up in a landfill. Especially when those things happen to be interesting pieces of vintage hardware. So the work [ekriirke] put in to get this early 1980’s era Sharp MemoWriter EL-7000 back up and running is definitely right up our alley.

There were a number of issues with the MemoWriter that needed addressing before all was said and done, but none more serious than the NiCd batteries popping inside the case. Battery leakage is a failure mode that most of us have probably seen more than a few times, but it never makes it any less painful to see that green corrosion spreading over the internals like a virus. When [ekriirke] cracked open this gadget he was greeted with a particularly bad case, with a large chunk of the PCB traces eaten away.

The corrosion was removed with oxalic acid, which dropped the nastiness factor considerably, but didn’t do much to get the calculator back in working order. For that, [ekriirke] reconnected each damaged trace using a piece of wire; he even followed the original traces as closely as possible so the final result looked a little neater. Once everything was electrically solid again, he covered the whole repair with a layer of nail polish to adhere the wires and add a protective coating. Nail polish might not have been our first choice for a sealer, and likely not that particular shade even if it was, but sometimes you’ve got to use what you have on hand.

After years of disuse the ribbon cartridge was predictably dry, so [ekriirke] rejuvenated it with the fluid from a permanent marker applied to the internal sponge. He also made some modifications to the battery compartment so he could insert rechargeable Ni-MH AA batteries rather than building a dedicated pack. There’s no battery door in the enclosure, so removing the batteries will require opening the calculator up, but at least he has the ability to remove the batteries before putting the device in storage. Should help avoid a repeat of what happened the first time.

If you’re a fan of a good restoration, we’ve got plenty to keep you entertained. From bringing a destroyed Atari back from the dead to giving some cherished children’s toys a new lease on life, fixing old stuff can be just as engrossing as building it from scratch.

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Tucoplexing: A New Charliplex For Buttons And Switches

March 23, 2019 by Kerry Scharfglass 28 Comments

Figuring out the maximum number of peripherals which can be sensed or controlled with a minimum number of IOs is a classic optimization trap with a lot of viable solutions. The easiest might be something like an i2c IO expander, which would give you N outputs for 4 wires (SDA, SCL, Power, Ground). IO expanders are easy to interface with and not too expensive, but that ruins the fun. This is Hackaday, not optimal-cost-saving-engineer-aday! Accordingly there are myriad schemes for using high impedance modes, the directionality of diodes, analog RCs, and more to accomplish the same thing with maximum cleverness and minimum part cost. Tucoplexing is the newest variant we’ve seen, proven out by the the prolific [Micah Elizabeth Scott] (AKA [scanlime]) and not the first thing to be named after her cat Tuco.

[Micah’s] original problem was that she had a great 4 port USB switch with a crummy one button interface. Forget replacement; the hacker’s solution was to reverse and reprogram the micro to build a new interface that was easier to relocate on the workbench. Given limited IO the Tucoplex delivers 4 individually controllable LEDs and 4 buttons by mixing together a couple different concepts in a new way.

Up top we have 4 LEDs from a standard 3 wire Charlieplex setup. Instead of the remaining 2 LEDs from the 3 wire ‘plex at the bottom we have a two button Charlieplex pair plus two bonus buttons on an RC circuit. Given the scary analog circuit the scan method is pleasingly simple. By driving the R and T lines quickly the micro can check if there is a short, indicating a pressed switch. Once that’s established it can run the same scan again, this time pausing to let the cap charge before sensing. After releasing the line if there is no charge then the cap must have been shorted, meaning that switch was pressed. Else it must be the other non-cap switch. Check out the repo for hardware and firmware sources.

Last time we talked about a similar topic a bunch of readers jumped in to tell us about their favorite ways to add more devices to limited IOs. If you have more clever solutions to this problem, leave them below! If you want to see the Twitter thread with older schematics and naming of Tucoplexing look after the break.

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The Tiniest RetroPie

January 29, 2019 by Bryan Cockfield 15 Comments

The RetroPie project is a software suite for the Raspberry Pi that allows the user to easily play classic video games through emulators. It’s been around for a while now, so it’s relatively trivial to get this set up with a basic controller and video output. That means that the race is on for novel ways of implementing a RetroPie, which [Christian] has taken as a sort of challenge, building the tiniest RetroPie he possibly could.

The constraints he set for himself were to get the project in at under 100 mm. For that he used a Pi Zero loaded with the RetroPie software and paired it with a 1.44″ screen. There’s a tiny LiPo battery hidden in there, as well as a small audio amplifier. Almost everything else is 3D printed including the case, the D-pad, and the buttons. The entire build is available on Thingiverse as well if you’d like to roll out your own.

While this might be the smallest RetroPie we’ve seen, there are still some honorable mentions. There’s one other handheld we’ve seen with more modest dimensions, and another one was crammed into an Altoids tin with a clamshell screen. It’s an exciting time to be alive!

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A Practical Portable Wii Emerges From The Memes

January 3, 2019 by Tom Nardi 6 Comments

A few months ago, [Shank] built what will almost certainly go down in history as the world’s smallest portable Nintendo Wii. As it turns out, the Wii motherboard is home to a lot of unnecessary hardware, and with a careful hand and an eye for detail, it’s possible to physically cut it down to a much smaller unit; allowing this particularly tenacious hacker to put an actual Wii, along with everything else required to make it portable, into an Altoids tin.

As you might expect, between the cramped controls, comically short battery life, and the fact that the whole thing got hot to the touch during use, it was a miserable excuse for a portable console. But the incredible response the project received inspired [Shank] to dust off an earlier project: a far more practical portable Wii that he calls PiiWii. This time around the handheld is a more reasonable size, a useful battery life, and proper controls. It even has an integrated “Sensor Bar” so you can use real Wii Remotes with it. It might not be the prettiest portable console conversion we’ve ever seen, but it certainly ranks up there as one of the most complete.

[Shank] actually “finished” the PiiWii some time ago, but in his rush to complete the project he got a little overzealous with the hot glue and ended up with a device that was difficult to diagnose and fix when things started to go wrong. He shelved the project and moved on to his Altoids tin build, which helped him refine his Wii shrinking skills. With a clearer head and some more practical experience under his belt, the PiiWii was revamped and is clearly all the better for it.

Unlike previous Wii portables we’ve seen, there’s no attempt at adding GameCube controller ports or video out capability. It’s built to be a purely handheld system, and that focus has delivered a system that’s roughly the size of the original Game Boy Advance. Beyond the cleverly sliced Wii motherboard, the inside of the PiiWii features a 3.5 inch display, a custom designed audio amplifier PCB, four 3400 mAh cells which deliver a run time of around four hours, a 3DS “slider” analog stick, and a generous helping of Kapton tape in place of hot glue.

If there’s any criticism of the PiiWii, it’s likely going to be about the system’s boxy exterior. But as [Shank] explains, there’s an excellent reason for that: it’s literally built into a project box. He simply took a commercially available ABS project box, the Polycase SL 57, and made all his openings on the front with a laser cutter. Other than the fact taking a laser to ABS releases hydrogen cyanide, he found it a good way to quickly knock out a custom enclosure.

Last year we took a look his ridiculously small Altoids tin Wii, and while that was an impressive project to be sure, we’re glad he revisited the PiiWii and showed that a portable Wii can be more than just a novelty. Compared to other systems, the Wii doesn’t seem to get the portable treatment that often, so we’re always glad to see somebody come in and do the concept justice.

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Get Your Tweets Without Looking

December 22, 2018 by Brian McEvoy 5 Comments

Head-mounted displays range from cumbersome to glass-hole-ish. Smart watches have their niche, but they still take your eyes away from whatever you are doing, like driving. Voice assistants can read to you, but they require a speaker that everyone else in the car has to listen to, or a headset that blocks out important sound. Ignoring incoming messages is out of the question so the answer may be to use a different sense than vision. A joint project between Facebook Inc. and the Massachusetts Institute of Technology have a solution which uses the somatosensory reception of your forearm.

A similar idea came across our desk years ago and seemed promising, but it is hard to sell something that is more difficult than the current technique, even if it is advantageous in the long run. In 2013, a wearer had his or her back covered in vibrator motors, and it acted like the haptic version of a spectrum analyzer. Now, the vibrators have been reduced in number to fit under a sleeve by utilizing patterns. It is being developed for people with hearing or vision impairment but what drivers aren’t impaired while looking at their phones?

Patterns are what really set this version apart. Rather than relaying a discrete note on a finger, or a range of values across the back, the 39 English phenomes are given a unique sequence of vibrations which is enough to encode any word. A ~~phenome~~ phoneme is the smallest distinct unit of speech. The video below shows how those phonemes are translated to haptic feedback. Hopefully, we can send tweets without using our hands or mouths to upgrade to complete telepathy.

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Building Portable Linux Devices: Never Been Easier, But Still Hard

November 30, 2018 by Jenny List 35 Comments

We live in a Golden Age of single-board computers. There was a time when a portable computer that was any good was a relatively rare and expensive device, certainly not something you could expect to replicate for yourself. A Psion, or later a Palm or perhaps a WinCE device would have been a lot more than an impulse purchase, and could not easily have been replicated using the components then available to the experimenter.

Thanks to spin-offs from technology developed for set-top boxes and mobile phones we can now buy any one of a pile of different boards that have almost equivalent power to a desktop computer. The experimenter can leverage that computing power to create their own small portables. Zerophone creator Arsenijs Picugins spoke about the tricky parts of designing a LInux portable at the recent Hackaday Superconference. You’ll find his talk below the break, which makes for a fascinating primer for those tempted to walk in his footsteps.

Minor Details of Portables are the Majority of the Build

In theory, it’s pretty easy to use one of these boards to make a portable computer. Take one of the smaller members of the Raspberry Pi or Beaglebone families, add a battery and a display, and away you go. But as always the devil is in the detail, and for a truly successful build there are a wealth of variables to attend to.

In his talk, Arsenijs takes us through the challenges of power supplies, connectors, and interfaces. In particular there is considerable challenge to running an SBC from a battery small enough to be portable, as efficiency concerns and the ability to easily recharge make for a critical set of choices. Then we learn of another pitfall, that of using USB as a default interface. Power loss in converting 5V to 3.3V that is inconsequential for a desktop computer is a battery-killer in a small device, so we’re pointed at the array of alternatives.

Zerophone screen menu [via @ZeroPhoneOSHW]

Screen Size is a Tricky Spec to Settle

If you’ve been tempted by one of those cheap Raspberry Pi touch screens, you’ll certainly understand that while a full desktop on a screen the size of a playing card looks cool, the reality is almost unusable. Your device will require a user interface that fits its form factor, which from his experience, Arsenijs suggests is best achieved through the medium of buttons rather than a touchscreen on smaller screens. There are a variety of UI and display libraries he introduces us to which make the whole process significantly easier.

Arsenijs’ Zerophone Raspberry Pi smartphone was a finalist in the 2017 Hackaday Prize, and remains an exemplary portable project from which many others can gain inspiration. We are privileged that he was able to bring his experience to speak at the Superconference, and his talk makes for a fascinating watch.

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Teardown Of A (Relatively) Cheap Thermal Camera

November 7, 2018 by Tom Nardi 32 Comments

The cost of tools and test equipment has largely been on the downward trend for years, making it now more affordable than ever to get into the hacking and making scene. This is particularly visible with something like the venerable oscilloscope: a piece of equipment that was near unobtainium for the home hacker a decade ago, you can now get digital pocket scope for as little as $20 USD. But there are still pieces of gear which haven’t quite hit the sort of prices we’d like to see.

A perfect example are thermal imaging cameras. The cheap ones are usually so low resolution they might as well just be thermometers, but the higher resolution ones can cost thousands. [Rob Scott] recently wrote in to tell us about a very promising middle ground, the HTI HT-A1. But he didn’t just point it out to us, he also tore it down and laid its internal’s bare for our entertainment. Now that’s our kind of introduction.

[Rob] walks us through the disassembly of the device, which is made unnecessarily difficult due to the fact that half the screws are hidden under a glued on screen bezel. That means a heat gun, a thin tool, and patience are in order if you want to get inside the device. It’s bad enough they use these kinds of construction techniques on modern smartphones, but at least they’re so thin that we can understand the reasoning. Why this chunky thing needs to resort to such measures is beyond us.

Eventually he cracks the HT-A1 open and is greeted with a single double-sided PCB. The top side is pretty much bare except for the buttons and the LCD display, and the flip side is largely just a breakout for a quad-core Allwinner A33 daughterboard. [Rob] theorizes this is to keep costs down by allowing reuse of the modular A33 board on other devices. Given the A33’s use in so many cheap tablets, it’s also possible HTI simply purchased these daughterboards as a drop-in component and designed their own board around it.

There’s not much else inside the HT-A1 beyond the rechargeable battery pack and thermal camera, both attached to the device’s rear panel. [Rob] noticed that the date on the thermal camera PCB is a full two years older than the date on the main PCB, leading one to wonder if HTI might have gotten a good deal on a bunch of these slightly outdated sensors and spun up a whole device around them.

The HT-A1 is high enough resolution that you can actually pick out individual components on a PCB, and at $400 USD is approaching a reasonable price point for the individual hacker. Which is not to say it’s cheap, but at least you get a useful tool for your money. We wouldn’t suggest you buy this device on a whim, but if you do a lot of diagnostic work, it might pay for itself after a couple repairs.

If that’s still a little too rich for your blood, we’ve covered a handful of DIY options which might better fit your budget.

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