A Slide Viewer Makes An Excellent Case For An OLED Project

June 17, 2016 by Jenny List 17 Comments

Sometimes when browsing the websites of our global hackspace community you notice a project that’s attractive not necessarily because of what it does or its technology but because of its presentation. So it is with the subject of this article, [Kris] needed a house temperature monitor and found a 1960s slide viewer made an excellent choice for its housing.

The monitor itself is a fairly straightforward Arduino build using a couple of DS18B20 1-wire temperature sensors and a real-time-clock module and displaying their readings on a small OLED screen. Its code can be found on this mailing list thread if you are interested. The display presented a problem as it needed to be reasonably large, yet fairly dim so it could be read at night without being bright enough to interrupt sleep.

A variety of projection techniques were tried, involving lenses from a projection clock, a magnifying glass, and a Google Cardboard clone. Sadly none of these lenses had the required focal length. Eventually the slide viewer was chosen because it was pointed out that the OLED screen was about the same size as a photographic slide.

Slide viewers are part of the familiar ephemera of the analog era that most people over 60 may still have taking up drawer space somewhere but may well be completely alien to anyone under about 30. They were a magnification system packaged up into a console usually styled to look something like a small portable TV of the day, and different models had built-in battery lights, or collected ambient light with a mirror. The screen was usually a large rectangular lens about 100mm(4″) diagonal.

[Kris]’s Vistarama slide viewer came via eBay. It’s not the smallest of viewers, other models folded their light paths with mirrors, however the extra space meant that the Arduino fit easily. The OLED was placed where the slide would go, and its display appeared at just the right magnification and brightness. Job done, and looking rather stylish!

We’ve not featured a slide viewer before here at Hackaday, though we did recently feature a similar hack on an Ikea toy projector. We have however featured more than one digital conversion on a classic slide projector using LCD screens in place of the slide.

Via Robots and Dinosaurs makerspace, Sydney.

Reverse Engineering A Nissan Leaf Battery Pack

June 16, 2016 by Jenny List 36 Comments

Batteries wear out. If you are an electric vehicle enthusiast, it’s a certainty that at some time in your not-too-distant future there will be a point at which your vehicle’s batteries have reached the end of their lives and will need to be replaced. If you have bought a new electric vehicle the chances are that you will be signed up to a leasing deal with the manufacturer which will take care of this replacement, but if you have an older vehicle this is likely to be an expensive moment.

Fortunately there is a tempting solution. As an increasing number of electric vehicles from large manufacturers appear on our roads, a corresponding number of them have become available on the scrap market from accident damage. It is thus not impossible to secure a fairly new lithium-ion battery pack from a modern electric car, and for a significantly lower price than you would pay for new cells. As always though, there is a snag. Such packs are designed only for the cars they came with, and have proprietary connectors and protocols with which they communicate with their host vehicle. Fitting them to another car is thus not a task for the faint hearted.

Hackaday reader [Wolf] has an electric truck, a Solectria E10. It has a set of elderly lead-acid batteries and would benefit hugely from an upgrade to lithium-ion. He secured a battery pack from a 2013 Nissan Leaf electric car, and he set about reverse engineering its battery management system (BMS). The Solectria will use a different battery configuration from the Leaf, so while he would like to use the Leaf’s BMS, he has had to reverse engineer its protocols so that he can replace its Nissan microcontroller with one of his own.

His description of the reverse engineering process is lengthy and detailed, and with its many photos and videos is well worth a read. He employs some clever techniques, such as making his own hardware simulation of a Li-ion cell so that he can supply the BMS known values that he can then sniff from the serial data stream.

We’ve covered quite a few EV batteries here at Hackaday. Quite recently we even covered another truck conversion using Leaf batteries, and last year we featured a Leaf battery teardown. We’ve not restricted ourselves to Nissan though, for example here’s a similar process with a Tesla Model S pack.

Lettuce For Life!

June 16, 2016 by Jenny List 68 Comments

If you take a head of romaine lettuce and eat all but the bottom 25mm/1inch, then place the cut-off stem in a bowl of water and leave it in the sun, something surprising happens. The lettuce slowly regrows. Give it a few nutrients and pay close attention to optimum growing conditions, and it regrows rather well.

This phenomenon caught the attention of [Evandromiami], who developed a home-made deep water culture hydroponic system to optimise his lettuce yield. The lettuce grows atop a plastic bucket of water under full spectrum grow lights, while an Intel Curie based Arduino 101 monitors and regulates light levels, humidity, temperature, water level, and pH. The system communicates with him via Bluetooth to allow him to tweak settings as well as to give him the data he needs should any intervention be required. All the electronics are neatly contained inside a mains power strip, and the entire hydroponic lettuce farm lives inside a closet.

He does admit that he’s still refining the system to the point at which it delivers significant yields of edible lettuce, but it shows promise and he’s also experimenting with tomatoes.

Our community have a continuing fascination with hydroponic culture judging by the number of projects we’ve seen over the years. This isn’t the first salad system, and we’ve followed urban farming before, but it’s winter strawberries that really catch the attention.

A Toasty Warm Pool Without The Propane Bills

June 15, 2016 by Jenny List 92 Comments

So, you’ve got the deck, you’ve got the pool and the lounger, you’ve got the summer, and you’ve got the piña colada. All set, you might say.

Sounds idilyic, but sadly we aren’t all lucky enough to live in a tropical climate. So while sipping the cocktail on the lounger you’d be warm enough the chances are that taking a dip would leave you feeling as though you’d just jumped into the Arctic Ocean. Not a problem, just turn on the pool heater. At this point you discover just how much it costs to heat a large body of water kept outdoors and open to the atmosphere. You become the kind of valued customer your liquid propane dealer sends a Christmas card to, you are reduced to living on a diet of budget ramen, and your children wear shoes with holes in them.

[ClanMan] had almost the problems outlined above, at least as far as the uncomfortable propane bills. His solution was a surprisingly simple one, he built himself a solar water heater from inexpensive PVC pipe.

It might not be immediately apparent to the uninitiated, but the key to making an efficient solar collector from such a basic material lies in careful selection of the bores of the various sections of pipe being used. The hot water feed from the propane heater had quite a narrow bore with a fast flow rate, but because [ClanMan] needed his water to linger in the collector and pick up as much solar heat as possible, he chose a much wider bore to feed it to ensure a much slower flow. The collector itself was made from multiple parallel lengths of much narrower pipe, to preserve the slow net flow across their combined cross-section while ensuring the maximum surface area contact between hot pipe and water.

The resulting heat helped take the temperature of his pool from 75 to 80 Farenheit. This may not sound like much, but was enough to make a noticeable difference.

We’ve featured quite a few solar heat projects before here at Hackaday. Best title has to go to the Hippie-Redneck Solar-Heated Kiddo Swimmin’ Pool And Hot Tub, but we’ve also featured a very tidy coiled solar collector. All this swimming is hungry work though, so how about a solar cooker made from a satellite dish?

Synchronize Data With Audio From A $2 MP3 Player

June 13, 2016 by Jenny List 32 Comments

Many of the hacks featured here are complex feats of ingenuity that you might expect to have emerged from a space-age laboratory rather than a hacker’s bench. Impressive stuff, but on the other side of the coin the essence of a good hack is often just a simple and elegant way of solving a technical problem using clever lateral thinking.

Take this project from [drtune], he needed to synchronize some lighting to an audio stream from an MP3 player and wanted to store his lighting control on the same SD card as his MP3 file. Sadly his serial-controlled MP3 player module would only play audio data from the card and he couldn’t read a data file from it, so there seemed to be no easy way forward.

His solution was simple: realizing that the module has a stereo DAC but a mono amplifier he encoded the data as an audio FSK stream similar to that used by modems back in the day, and applied it to one channel of his stereo MP3 file. He could then play the music from his first channel and digitize the FSK data on the other before applying it to a software modem to retrieve its information.

There was a small snag though, the MP3 player summed both channels before supplying audio to its amplifier. Not a huge problem to overcome, a bit of detective work in the device datasheet allowed him to identify the resistor network doing the mixing and he removed the component for the data channel.

He’s posted full details of the system in the video below the break, complete with waveforms and gratuitous playback of audio FSK data.

Continue reading “Synchronize Data With Audio From A $2 MP3 Player” →

A Hot Rod Roadster From A Rusty Wreck

June 12, 2016 by Jenny List 20 Comments

Within our community of hackers and makers you may sometimes encounter a belief that we have somehow regained a hold on the workshop lost by everyone else. But while it might be true that some of the general population may barely know one end of a screwdriver from the other it’s a huge overstatement to claim exclusivity. There are plenty of other scenes blessed with an astonishing level of engineering skill and from which breathtaking projects emerge, and it is a great pity that sometimes they exist in isolation from each other.

One such scene is that of car modification. By this we don’t mean the youths with their inadequately powered bottom-feeder cars adorned with deformed plastic, fake carbon fibre and farty exhaust pipe extensions from Halfords or Advance Auto, nor do we mean the silly-priced professional hotrods beloved of certain cable TV reality shows. Instead we mean the ordinary car hackers who take the unexciting and unloved of the automotive world into their garages and through a combination of vision and skill fashion it into something amazing. As an illustration of this art we’d like to introduce you to [ScaryOldCortina]’s “Mayday”. It’s a build from a few years ago, but no less impressive for the elapsed time.

If you are British the chances are your grandparents might have driven an Austin Somerset in the early 1950s. An unexciting mid-sized chassis-based saloon car that wasn’t badly designed but had all the inadequate rust protection you’d expect from a car of that era. A Somerset arrived in [ScaryOldCortina]’s garage that looked solid but turned out on inspection to be rusty enough that it could almost be disassembled with a hefty tug on some of the panels. He could have scrapped it, but instead he refashioned it into something a lot more exciting, a two-seater hotrod roadster. In a particularly impressive touch, he re-used most of the metal from the Somerset in its new body in a different form, for example its curved roof was cut in half to form the side panels of the new car.

The full build is in a very long thread on the Retro Rides car forum. If you read it from start to finish you’ll find an in-depth description of the minutiae of the 1950s British car parts bin, but if that will be a bit much for you we have some highlights.

When the car arrived, in his first post you can see just how far the rust had eaten into an outwardly complete vehicle and how easily he could strip away its panels. Fortunately the Somerset is a chassis-based car, so underneath the rusty bodywork was a rolling chassis which had miraculously escaped the worst of the corrosion. His vision for the car required the chassis to be shortened, but he was able to place the panels on the chassis to get an idea of what it might look line before getting out the cutter and welder and assembling the new body tub. A lot of hard work assembling the running gear into a roadworthy form and making its unlovely Austin “B” series engine into something a little more useful, and he was finally able to take it for a short test drive. The car passed all the relevant tests for British roadworthiness, and made a very cool piece of transport.

Happily though it’s the first to feature so much rust this is not the first Hackaday story involving the hacking of ancient automobiles. We recently had a look at the hacking potential of Volkswagen’s iconic Beetle, we’ve examined the work of professional TV hot-rodders when challenged over their authenticity, we’ve taken a look at Cuba’s surviving pre-revolutionary American cars, and we’ve featured a crazy project involving a Mini and a Toyota Celica.

Retrotechtacular: An Unexpected Meeting With Philo T Farnsworth

June 12, 2016 by Jenny List 26 Comments

It is not often that you look for one of your heroes on the Internet and by chance encounter another from a completely different field. But if you are a fan of the inimitable silent movie star [Buster Keaton] as well as being the kind of person who reads Hackaday then that could have happened to you just as it did here.

Our subject today is a 1957 episode of CBS’s TV game show I’ve Got a Secret! in which [Keaton] judges a pie-eating contest and is preceded first by a young man with a penchant for snakes and then rather unexpectedly by a true giant of twentieth century technology.

[Philo T Farnsworth] was a prolific engineer who is probably best known as the inventor of electronic television, but whose work touched numerous other fields. Surprisingly this short segment on an entertainment show was his only appearance on the medium to which his invention helped give birth. In it he baffles the panel who fail to guess his claim to fame, before discussing his inventions for a few minutes. He is very effacing about his achievement, making the point that the development of television had been a cumulative effort born of many contributors. He then goes on to discuss the future of television, and talks about 2000-line high-definition TV with a reduced transmission bandwidth, and TV sets like picture frames. All of which look very familiar to us nearly sixty years later in the early 21st century.

The full show is below the break, though [Farnsworth]’s segment is only from 13:24 to 21:24. It’s very much a show of its time with its cigarette product placement and United Airlines boasting about their piston-engined DC-7 fleet, but it’s entertaining enough.

Continue reading “Retrotechtacular: An Unexpected Meeting With Philo T Farnsworth” →