ZX81 Emulated On An Mbed

This is a wonderful example of the phenomenon of “feature creep”. [Gert] was working on getting a VGA output running on an mbed platform without using (hardly) any discrete components. Using only a few resistors, the mbed was connected to a VGA display running at 640×480. But what could he do with something with VGA out? He decided to emulate an entire Sinclair ZX81 computer, of course.

With more than 1.5 million units sold, the Sinclair ZX81 was a fairly popular computer in the early ’80s. It was [Gert]’s first computer, so it was a natural choice for him to try to emulate. Another reason for the choice was that his mbed-VGA device could only output monochrome color, which was another characteristic of the ZX81.

[Gert] started by modifying a very lean Z80 emulator to make the compiled code run as efficiently as possible on the mbed. Then he went about getting a picture to display on the screen, then he interfaced an SD card and a keyboard to his new machine. To be true to the original, he built everything into an original ZX81 case.

This isn’t the first time we’ve seen a ZX81, but it is one of the better implementations of an emulated version of this system we’ve seen.

Thanks to [Jeroen] for the tip!

Smart CPR Dummy Makes Sure You Do It Right

Have you ever taken a First Aid & CPR training course? Don’t you just love the realism of the dummy mannequins you get to practice on? [Park, Qurashi, & Chen], who are students of Cornell University, thought the dummies could use an intelligent upgrade.

It’s the final project for their electrical and computer engineering course ECE 4760. And what they’ve done is successfully created a budget friendly CPR not-so-dumb dummy using the venerable ATmega1284 microcontroller.

The dummy can sense when chest compressions are given, if the nose is plugged properly when breaths are given, if the head is tilted back properly to open the airway, and it even makes use of a microphone to detect if breaths are given properly! While it does this, it uses LED eyes and an LCD screen to provide training feedback to the student. Once the students are sufficiently practiced, it also has a “real” mode that doesn’t give you any feedback to make sure the students truly learned the technique. Continue reading “Smart CPR Dummy Makes Sure You Do It Right”

Developing Film With Lego

Developing film at home is most certainly a nearly forgotten art nowadays, but there are still a few very dedicated people who care enough to put in the time and study to this craft. [Jan] is one of the exceptional ones. He’s developing 35mm film with Lego (Dutch, Google translate).

For the build, [Jan] is using the Lego RCX 1.0, the first gen of the Lego Mindstorms, released in the late 90s. According to eBay, this is a significantly cheaper option for programmable Lego. The mechanics of the Lego film developer consisted of multiple tanks of chemicals. The film was loaded on a reel, suspended from a Lego gantry, and dunked into each tank for a specific amount of time.

A second revision of the hardware (translate) was designed, with the film loaded into a rotating cylinder. A series of chemicals would then be pumped into this unit with the hope of reducing the amount of chemicals required. This system was eventually built using the wiper fluid pump from a car. Apparently, the system worked well, judging from the pictures developed with this system. Whether it was easy or efficient is another matter entirely.

You can check out a video of the first revision of the Lego film developing system below.

Thanks [Andrew] for sending this in.

Continue reading “Developing Film With Lego”

Micro Tesla Coil Makes A Perfect Stocking Stuffer

Tesla coils are always a hit around here at the office. Giant ones that play music with modern-day chain mail wearing DJ’s, ones thrown together in garages by self-proclaimed mad scientists… But have you ever seen one that can fit in the palm of your hand?

[Ludic Science] just released this tutorial video on how to make it. It’s a miniature diagram of slayer circuitsolid state Tesla coil that’s based on the ever popular Slayer Exciter circuit that was first developed by [GBluer]. The beauty is it’s a very simple circuit to build. It consists of one power transistor, a few diodes, some resistors, and the coil. That’s it!

He even repurposes the magnet wire from a small relay, it’s literally a project you can build from scrap parts around the shop. Awesome.

Continue reading “Micro Tesla Coil Makes A Perfect Stocking Stuffer”

The Heathkit Mystery

Heathkit is a company that requires no introduction. From the mid-40s until the 90s, Heathkit was the brand for electronic kits ranging from test equipment, HiFis, amateur radio equipment, computers, to freakin’ robots. Their departure was a tragic loss for generations of engineers, electronic tinkerers and hobbyists who grew up with these excellent and useful kits.

Although Heathkit is dead, 2013 brought an announcement that Heathkit was back in the biz. A Facebook page was launched, a Reddit AMA was held, and the news was that Heathkit would rise from the dead in the first half of 2014. It’s now Christmas, 2014, and there’s no sign of Heathkit anywhere. Adafruit has been keeping a watchful eye on the on the (lack of) developments, and the only surprising thing to report is that there is nothing to report. There has been no new announcement, there are no new products, the “official” Heathkit website hasn’t been updated in a year, and no one knows what’s going on.

Adafruit has decided to dig into the matter, and while they’ve come up with a few items of note, there’s not much to report. A trademark for ‘HEATHKIT’ was filed October 27, 2014 – two months ago. An email was sent to the attorney of record and there has been no response.

This trademark was granted to Heathkit Company, Inc., incorporated in Delaware. Searching for any companies in Delaware using the Heathkit name returns exactly two results: Heathkit Company, Inc., and Heathkit Holdings, Inc.. Adafruit is probably going to pay the $20 to the Delaware Department of State to get the detailed information that includes Heathkit’s tax assessment and tax filing history.

The last bit of information comes from a whois on the heathkit.com domain. The relevant contacts have been emailed, and there are no further details. The Heathkit virtual museum was contacted for information, as was the news editor for ARRL.org. Nobody knows anything, or at least nobody is telling anybody anything.

To date, the only physical evidence of Heathkit’s rebirth is a geocache that was left at Brooklyn Bridge Park, announced during the Reddit AMA. This geocache was recovered by reddit user IFoundTheHeathKit, a throwaway account that had no posts before or since finding the cache. We have no idea what was in that geocache, what the ‘secret passphrase’ or set of instructions was, or if anything ever came of the promise to send one of the first new kits.

So there ‘ya go. A lot of words but no information. If you have any info, the Adafruit crew would like to have a word with you.

Update

The person who found the Heathkit geocache has been found:

 

 

 

 

 

 

 

 

 

The full comment referred to below is,

Hey, person who found the Heathkit geocache here. The secret passcode was an Einstein quote about radio vs wired communication (invisible cats), and they said they’d send me something in early 2014. Never had any communication except through FB, and they haven’t replied to any of my recent messages.

IFoundTheHeathKit might want to email Adafruit with a copy of all the emails.

$50k In Components Hit The Hands Of Hackaday Prize Semifinalists

We anticipate a cornucopia of hacks from the top fifty 2014 Hackaday Prize entrants based on the recent awarding of the 50 grab bags of electronics. That’s right, the grand prize was out of this world but there were a lot of other rewards worth shooting for. Instead of making hardware choices without the seminifinalists’ input we went with a shopping spree on Mouser.com.

It’s a great idea if we do say so ourselves. However, it turned out not to be as easy as purchasing fifty-grand in gift cards. Did you know that none of the major parts distributors have gift card systems built into their sites? We’re of two minds on this. We’d love to open a birthday card from grannie and pull out some chits that can be traded for chips. But at the same time, it would be a longshot for your non-hacker relatives to even know what sites are our go-to parts emporiums.

Long story short these prizes are themselves a hack. We had a lot of help from the sales crew over at Mouser who abused their account tracking software in order to make these credits work. All fifty of the Hackaday prize semifinalists now have a cool G to spend and we’ll be watching their Hackaday.io accounts for updates as they inevitably use the upcoming holidays to embark on exciting builds.

A big thanks to Supplyframe Inc. for sponsoring these 50 prizes, as well as all others awarded for the 2014 Hackaday Prize. Get those workbenches cleared off and sharpen tin your soldering tips because details about the 2015 Hackaday Prize will start to roll out in just a few weeks. Until then, occupy your time trying to win one of the many prizes offered during our Trinket Everyday Carry Contest.

Green-Sweep For Your Ultrasonic Rangefinder

Maybe you’ve never programmed an Arduino before. Or maybe you have, but nothing beyond das blinkenlights. Maybe your soldering iron sits in a corner of your garage, gazing at you reproachfully every time you walk by, like a ball begging to be thrown. Maybe you’ve made a few nifty projects, but have never interfaced them with a PC. If this describes you, then this article and project is just what you need. So grab your favorite beverage, tuck in and prepare to get motivated.

[Anuj Dutt] has not only made a really cool project, he has also done a most excellent job at documenting it. It’s an Arduino controlled “RADAR” like project that uses the familiar Parallax ultrasonic sensor. It’s mounted to a servo and feeds data to a PC where a custom VB.NET program translates the data in to a cool “green radar sweep” screen. It also pushes text to an LCD which reveals the distance from the target.

screenshot of radar program

[Anuj Dutt] hand rolled his Arduino just because, but ran into some trouble getting everything to talk to the PC. He wound up using the ultra user friendly FTDI to save the day. Be sure to check out the video below to see the project in action. [Anuj] published the code for both the Arduino and PC in the video description.

Continue reading “Green-Sweep For Your Ultrasonic Rangefinder”