Fail Of The Week: How NOT To Smooth A 3D Print

August 16, 2016 by Dan Maloney 78 Comments

Many of the Fail Of The Week stories we feature here are pretty minor in the grand scheme of things. At worse, gears are ground, bits are broken, or the Magic Blue Smoke is released. This attempt to smooth a 3D print released far more than a puff of blue smoke, and was nearly a disaster of insurance adjuster or medical examiner proportions.

Luckily, [Maxloader] and his wife escaped serious injury, and their house came out mostly unscathed. The misadventure started with a 3D printed Mario statue. [Maxloader] had read acetone vapor can smooth a 3D print, and that warming the acetone speeds the process. Fortunately, his wife saw the looming danger and wisely suggested keeping a fire blanket handy, because [Max] decided to speed the process even more by putting a lid on the pot. It’s not clear exactly what happened in the pot – did the trapped acetone vapors burp the lid off and find a path to the cooktop burner? Whatever it was, the results were pretty spectacular and were captured on a security camera. The action starts at 1:13 in the video below. The fire blanket came in handy, buying [Max] a few seconds to open the window and send the whole flaming mess outside. Crisis averted, except for nearly setting the yard on fire.

What are we to learn from [Maxloader]’s nearly epic fail? First, acetone and open flame do not mix. If you want to heat acetone, do it outside and use an electric heat source. Second, a fire extinguisher is standard household equipment. Every house needs at least one, and doubly so when there’s a 3D printer present. And third, it’s best to know your filaments – the dearly departed Mario print was in PLA, which is best smoothed with tetrahydrofuran, not acetone.

Anything else? Feel free to flame away in the comments.

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Retrotechtacular: Tom Carter Revolutionized Your Phone

August 16, 2016 by Al Williams 40 Comments

It is hard to remember, but there was a time when you couldn’t hook much to a telephone line except a telephone. Although landlines are slowly falling out of favor, you can still get corded and wireless phones, answering machines, and even dial up modems. Alarm systems sometimes connect to the phone system along with medical monitoring devices and a host of other accessories.

All of that’s possible because of a Texan named Tom Carter. Tom Carter was the David that stood up to one of the biggest Goliath’s of his day: the phone company. The phone company had a legal monopoly on providing phone service. The reasoning was that it didn’t make sense to have multiple competing companies trying to run wires to every house and business in the country. Makes sense, right?

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Ask Hackaday: What Are Magnetic Gears (Good For)?

August 15, 2016 by Moritz Walter 51 Comments

Magnetic gears are surprisingly unknown and used only in a few niche applications. Yet, their popularity is on the rise, and they are one of the slickest solutions for transmitting mechanical energy, converting rotational torque and RPM. Sooner or later, you’re bound to stumble upon them somewhere, so let’s check them out to see what they are and what they are good for.

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History Of The Diode

August 15, 2016 by Steven Dufresne 46 Comments

The history of the diode is a fun one as it’s rife with accidental discoveries, sometimes having to wait decades for a use for what was found. Two examples of that are our first two topics: thermionic emission and semiconductor diodes. So let’s dive in.

Vacuum Tubes/Thermionic Diodes

Our first accidental discovery was of thermionic emission, which many years later lead to the vacuum tube. Thermionic emission is basically heating a metal, or a coated metal, causing the emission of electrons from its surface.

In 1873 Frederick Guthrie had charged his electroscope positively and then brought a piece of white-hot metal near the electroscope’s terminal. The white-hot metal emitted electrons to the terminal, which of course neutralized the electroscope’s positive charge, causing the leafs to come together. A negatively charged electroscope can’t be discharged this way though, since the hot metal emits electrons only, i.e. negative charge. Thus the direction of electron flow was one-way and the earliest diode was born.

Thomas Edison independently discovered this effect in 1880 when trying to work out why the carbon-filaments in his light bulbs were often burning out at their positive-connected ends. In exploring the problem, he created a special evacuated bulb wherein he had a piece of metal connected to the positive end of the circuit and held near the filament. He found that an invisible current flowed from the filament to the metal. For this reason, thermionic emission is sometimes referred to as the Edison effect.

Thermionic diode. By Svjo [CC BY-SA 3.0], via Wikimedia Commons

But it took until 1904 for the first practical use of the effect to appear. John Ambrose Fleming had actually consulted for the Edison Electric Light Company from 1881-1891 but was now working for the Marconi Wireless Telegraph Company. In 1901 the company demonstrated the first radio transmission across the Atlantic, the letter “S” in the form or three dots in Morse code. But there was so much difficulty in telling the received signal apart from the background noise, that the result was disputed (and still is). This made Fleming realize that a more sensitive detector than the coherer they’d been using was needed. And so in 1904 he tried an Edison effect bulb. It worked well, rectifying the high frequency oscillations and passing the signals on to a galvanometer. He filed for a patent and the Fleming valve, the two element vacuum tube or thermionic diode, came into being, heralding decades of technological developments in many subsequent types of vacuum tubes.

Vacuum tubes began to be replaced in power supplies in the 1940s by selenium diodes and in the 1960s by semiconductor diodes but are still used today in high power applications. There’s also been a resurgence in their use by audiophiles and recording studios. But that’s only the start of our history.

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Hackaday Links: August 14, 2016

August 14, 2016 by Brian Benchoff 40 Comments

Hey London peeps! Hackaday and Tindie are doing a London meetup! It’s this Wednesday, the 17th.

What do you do if you need Gigabytes of storages in the 80s? You get tape drives. What do you do if you need Terabytes of storage in the year 2000? You get tape. The IBM Totalstorage 3584 is an automated tape storage unit made sometime around the year 2000. It held Terabytes of data, and [Stephen] picked up two of them from a local university. Here’s the teardown. Unfortunately, there’s no footage from a GoPro stuck inside the machine when it’s changing tapes, but the teardown was respectable, netting two drives, the power supplies, and huge motors, fans, relays, and breakers.

A few years ago Motorola released the Lapdock, a CPU-less laptop with inputs for HDMI and USB. This was, and still is, a great idea – we’re all carrying powerful computers in our pocket, and carrying around a smartphone and a laptop is effort duplication. As you would expect, the best use for the Lapdock was with a Raspberry Pi, and prices of Lapdocks have gone through the roof in the last few years. The Superbook is the latest evolution of this Lapdock idea. It’s a small, thin, CPU-less laptop that connects to a phone using a special app and a USB cable. It also works with the Raspberry Pi. Very interesting, even if they didn’t swap the CTRL and Caps Lock keys as God intended.

Did you know we have a store? Yes! It’s true! Right now we need to get rid of some stuff, so we’re having a clearance sale. We got FPGA Arduino shields! Buy a cordwood puzzle! SUPERLIMINAL ADVERTISING.

The computers aboard Federation vessels in the 24th century were based on isolinear chips. Each chip plugged into a backplane, apparently giving certain sections of the ship different functions. Think of it as a reconfigurable PDP Straight-8. This is canon, from TNG, and doesn’t make any sense. [Bohrdasaplank] over on Thingiverse has a few different models of isolinear chips. After close examination of these chips, we can only come to one conclusion.

How do you get a pilot bearing out of a motor? The normal way is using grease (or caulk, or some other gooey substance) as a hydraulic ram, but a slice of bread works much better. This is a weird one, but it works perfectly, with hardly any cleanup whatsoever.

542-page PDF warning here. Here’s the operations manual for the Apollo 15, including operation of the AGC, how to fly the LM, the planned traverses and EVAs, and a nice glossary of handy equations. If anyone’s looking for a LaTeX, InDesign, or bookbinding project that would make the perfect bathroom reader, this is it.

Here’s something I’ve been having trouble with. This is an mATX computer case with a screen on the side and a cover for the screen that includes a keyboard and trackpad. Yes, it’s a modern version of the luggable, ‘portable’, plasma-screen monsters of the 80s. I don’t know where I can buy just the case, so I’m turning to the Hackaday community. There’s an entire line of modern luggable computers made by some factory in Taiwan, but as far as I can tell, they only sell to resellers who put their own mobo and CPU in the machine. I just want the case. Where can I buy something like this? If you’re asking why anyone would want something like this, you can put two 1080s in SLI and still have a reasonably portable computer. That’s a VR machine, right there.

Hacklet 120 – Coffee Hacks

August 13, 2016 by Adam Fabio 31 Comments

Hackers need fuel to hack. In general that fuel comes in the form of food, water, and caffeine. Not necessarily in that order. While soda or energy drinks will do in a pinch, the best hackers know that the purest form of caffeine comes from coffee. This of course means that there have been decades of coffee hacks. The first Internet-connected coffee pot dates all way back to 1991, before the web even had pictures. We’ve come a long way since then. This week on the Hacklet we’re checking out some of the best coffee hacks on Hackaday.io!

We start with [opeRaptor] and CoffeeOfThings. [OpeRaptor] has created a wireless, internet connected coffee carafe. The carafe has three CdS cells which enable it to detect how much black gold is left in the pot. A TMP36 sensor reports the current coffee temperature. Data is sent out via a NRF24l01 radio. The brains of the coffee pot is an MSP430 microcontroller. All this runs from a simple CR2032 coin cell. A base station receives the coffee data, displays it on a very nice Vacuum fluorescent Display (VFD). An ESP8266 then passes the data on to the internet.

Next up is [magnustron] with quad-386 coffee heater. No one likes a cold cup of coffee. Everyone loves old CPUs. [Magnustron] turned these two shower thoughts into a the world’s first USB powered quad CPU coffee warmer with data logging capabilities. A simple ATtiny461 micro runs the show. PC connectivity is via USB using the V-USB library. [Magnustron] has gotten the CPUs to warm up, but is having some issues with switching. them on. Turning all four heaters on too quickly causes the rail to droop, leading to dropped USB connections. Those power-hungry 386 chips may be a bit too much for a single USB connection. It might be time to add an external power supply.

Next is [kesh1030] with Using Waste Coffee As A Biodiesel Source. Coffee isn’t just liquid energy. There’s oil in them there grounds. Millions of pounds of used coffee grounds produced every year can be converted to biodiesel fuel. [Kesh1030] experimented with different coffee grounds, and different ways to prepare them. The oil was extracted from the coffee using hexane, which is a bit of a nasty solvent. [Kesh1030] used a fume hood to stay safe. He found that homogenized coffee grounds had an 11.87% oil yield. Used homogenized coffee grounds weren’t far behind, with 9.82% yield of oil. Nearly 10% per weight yield isn’t too shabby, considering this is all going into the trash.

Finally, we have [saadcaffeine] with Caffeinator: gravity powered geek fuel dripper. This is a project of few words, but the images tell much of the story. [Saadcaffeine] created his own cold drip iced coffee maker using upcycled and found components. Three clothes hangers form an ingenious tripod. The tripod holds two soda bottles – the water reservoir and the brew pot. Water is restricted by small holes in the soda bottle caps. This allows it to drop slowly though the machine, giving it time to soak up all the caffeinated goodness. The result is a fresh cup of cold drip. Just add ice and enjoy a quick power up!

If you want to see more coffee hacks, check out our new coffee projects list. See a project I might have missed? Don’t be shy, just drop me a message on Hackaday.io. That’s it for this week’s Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Tearing Into Delta Sigma ADCs Part 2

August 11, 2016 by Bil Herd 21 Comments

In part one, I compared the different Analog to Digital Converters (ADC) and the roles and properties of Delta Sigma ADC’s. I covered a lot of the theory behind these devices, so in this installment, I set out to find a design or two that would help me demonstrate the important points like oversampling, noise shaping and the relationship between the signal-to-noise ratio and resolution.

Modulator Implementation

Check out part one to see the block diagrams of what what got us to here. The schematics shown below are of a couple of implementations that I played with depicting a single-order and a dual-order Delta Sigma modulators.

Basically I used a clock enabled, high speed comparator, with two polarities in case I got it the logic backwards in my current state of burn out to grey matter ratio. The video includes the actual schematic used.

Since I wasn’t designing for production I accepted the need for three voltages since my bench supply was capable of providing them and this widget is destined for the drawer with the other widgets made for just a few minutes of video time anyway. Continue reading “Tearing Into Delta Sigma ADCs Part 2” →