Fail Of The Week: Teddy Top And Fourteen Fails

December 11, 2014 by Brian Benchoff 72 Comments

Last summer, [Quinn] made the trip out to KansasFest, the annual Apple II convention in Kansas City, MO. There, she picked up the most modern Apple II system that wasn’t an architecturally weird IIGS: she lugged home an Apple IIc+, a weird little machine that looks like an old-school laptop without a screen.

Not content with letting an old computer just sit on a shelf looking pretty, [Quinn] is working on a project called the Teddy Top. ‘Teddy’ was one of the code names for the Apple IIc, and although add-ons to turn this book-sized computer into something like a laptop existed in the 80s, these solutions have not withstood the test of time. [Quinn] is building her own clamshell addition to her IIc+, and somehow failing at something she’s done hundreds of times before.

While the IIc+ has an NTSC composite output, the super-special video add-ons for the IIc+ used a DB15 expansion connector. Here, any add-on could access video sync signals, the a sound signal from the audio circuit, and even a +12V line that could drive loads up to 300 mA. It just so happened the display [Quinn] is using for this project runs at 12V, 200 mA. Everything was great, but as a worthy trustee of this computer’s Earthly existence, [Quinn] thought a bit of current limiting should be included in her addon. She designed a circuit around an NPN power transistor, that would allow the display to draw power until the load was around 250mA. After that, the transistor would start dumping excess power as heat. Yes, a fuse would be better. [Quinn] calls this Fail #1. There are thirteen more to go.

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Retrotechtacular: Supersonic Transport Initiatives

December 9, 2014 by Kristina Panos 17 Comments

In the early days of PBS member station WGBH-Boston, they in conjunction with MIT produced a program called Science Reporter. The program’s aim was explaining modern technological advances to a wide audience through the use of interviews and demonstrations. This week, we have a 1966 episode called “Ticket Through the Sound Barrier”, which outlines the then-current state of supersonic transport (SST) initiatives being undertaken by NASA.

MIT reporter and basso profondo [John Fitch] opens the program at NASA’s Ames research center. Here, he outlines the three major considerations of the SST initiative. First, the aluminium typically used in subsonic aircraft fuselage cannot withstand the extreme temperatures caused by air friction at supersonic speeds. Although the Aérospatiale-BAC Concorde was skinned in aluminium, it was limited to Mach 2.02 because of heating issues. In place of aluminium, a titanium alloy with a melting point of 3,000°F is being developed and tested.

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Scope Noob: Microcontroller Quirks With DDS

December 9, 2014 by Mike Szczys 40 Comments

In this installment of Scope Noob I’m working with Direct Digital Synthesis using a microcontroller. I was pleasantly surprised by some of the quirks which I discovered during this process. Most notably, I had a chance to look at errant triggers solved by using holdoff and a few timing peculiarities introduced by my use of the microcontroller. Here’s a video synopsis but I’ll cover everything in-depth after the break.

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Hacklet 25 – ESP8266 WiFi Module Projects

December 5, 2014 by Adam Fabio 6 Comments

Few devices have hit the hacker/maker word with quite as large a bang as the ESP8266. [Brian] first reported a new $5 WiFi module back in August. Since then there have been an explosion of awesome projects utilizing the low-cost serial to WiFi module that is the ESP8266. This week’s Hacklet is all about some of the great ESP8266 projects we’ve found on Hackaday.io!

We start with [TM] and the ESP8266 Retro Browser. [TM] has a great tutorial on combining the ESP8266 with an Arduino Mega2560. [TM’s] goal was a simple one: create a WiFi “browser” to access Hackaday’s Retro Site. This is a bit more complex than one would first think, as the Arduino Mega2560 is a 5V board, and the ESP8266 are 3.3V parts. Level shifters to the rescue! [TM] was able to bring up the retro site in a terminal, but found that even “simple” websites like google send enough data back to swap the poor ESP8266!

Next up is [Thomas] with the Simple Native ESP8266 Smartmeter. [Thomas] has created a device to measure run time on his oil heating system. He implemented this with some native programming on the ESP8266’s onboard Diamond Standard L106 Controller. When he was done, the ‘8266 had two new AT commands, one to start measurement and one to stop. A bit of web magic with some help from openweathermap.org allows [Thomas] to plot oil burner run time against outside temperature.

[Matt Callow] is also checking out native programming using the EspressIf sdk with his project ESP8266 Native. ExpressIf made a great choice when they released the SDK for the ESP8266 back in October. [Matt] has logged his work on building and extending the demo apps from EspressIf. [Matt] has seven demo programs which do everything from blinking an LED to connecting to thingspeak via WiFi. While the demos aren’t all working yet, [Matt] is making great progress. The best part is he has all his code linked in from his Github repo. Nice work [Matt!]

[Michael O’Toole] is working on ESP8266 Development PCBs. The devboards have headers for the ESP8266, an on-board ATmega328 for Arduino Uno compatibility, and a USB to serial converter to make interfacing easy. [Michael] also provides all the important components you need to keep an ESp8266 happy, such as programming buttons, and a 3.3V regulator. We really like that [Michael] has included a header for a graphical LCD based local console.

Want to see more ESP8266 goodness? Check out our curated ESP8266 list on Hackaday.io!

Hackaday.io Update!

Hackaday.io gets better and better every day. We’ve just pushed out a new revision which includes some great updates. Search is now much improved. Try out a search, and you’ll find you can now search by project, project log, hacker, or any combination of 11 different fields. Our text editor has been revamped as well. Update a project log to give the new look a try!
We know everyone on .io is awesome, but just in case a spammer slips in, we’ve added “report as inappropriate” buttons to projects and comments. Once a few people hit those report buttons, projects or comments get sent to the admins for moderation.

That’s all the time we have for this week’s Hacklet! As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Scope Noob: Bridge Rectifier

December 3, 2014 by Mike Szczys 58 Comments

Welcome back to this week’s installment of Scope Noob where I’m sharing my experiences learning to use my first oscilloscope. Last week I started out measuring mains frequency using an AC-AC wall wart adapter. Homework, for those following along, was to build a bridge rectifier and probe the signals from it. Let’s take a look.

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Retrotechtacular: Ma Bell’s Advanced Mobile Phone Service (AMPS)

December 2, 2014 by Kristina Panos 14 Comments

This gem from the AT&T Archive does a good job of explaining the first-generation cellular technology that AT&T called Advanced Mobile Phone Service (AMPS). The hexagon-cellular network design was first conceived at Bell Labs in 1947. After a couple of decades spent pestering the FCC, AT&T was awarded the 850MHz band in the late 1970s. It was this decision coupled with the decades worth of Bell System technical improvements that gave cellular technology the bandwidth and power to really come into its own.

AT&T’s primary goals for the AMPS network were threefold: to provide more service to more people, to improve service quality, and to lower the cost to subscribers. Early mobile network design gave us the Mobile Service Area, or MSA. Each high-elevation transmitter could serve a 20-mile radius of subscribers, a range which constituted one MSA. In the mid-1940s, only 21 channels could be used in the 35MHz and 150MHz band allocations. The 450MHz band was introduced in 1952, provided another 12 channels.

The FCC’s allocation opened a whopping 666 channels in the neighborhood of 850MHz. Bell Labs’ hexagonal innovation sub-divided the MSAs into cells, each with a radius of up to ten miles.

The film explains quite well that in this arrangement, each cell set of seven can utilize all 666 channels. Cells adjacent to each other in the set must use different channels, but any cell at least 100 miles away can use the same channels. Furthermore, cells can be subdivided or split. Duplicate frequencies are dealt with through the FM capture effect in which the weaker signal is suppressed.

Those Bell System technical improvements facilitated the electronic switching that takes place between the Mobile Telephone Switching Office (MTSO) and the POTS landline network. They also realized the automatic control features required of the AMPS project, such as vehicle location and automatic channel assignment. The film concludes its lecture with step-by-step explanations of inbound and outbound call setup where a mobile device is concerned.

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Ask Hackaday: What Is The Future Of Virtual Reality?

November 28, 2014 by Will Sweatman 32 Comments

Most of us have heard of Second Life – that antiquated online virtual reality platform of yesteryear where users could explore, create, and even sell content. You might be surprised to learn that not only are they still around, but they’re also employing the Oculus Rift and completely redesigning their virtual world. With support of the DK2 Rift, the possibilities for a Second Life platform where users can share and explore each other’s creations opens up some interesting doors.

Envision a world where you could log on to a “virtual net”, put on your favorite VR headset and let your imagination run wild. You and some friends could make a city, a planet…and entire universe that you and thousands of others could explore. With a little bit of dreaming ~~and an arduino~~, VR can bring dreams to life.

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