Hackaday Links: Christmas Eve, 2012

It’s Christmas Eve, the perfect time to interact with your extended familial units, eat cookies, nog things up a little, and watch Die Hard. Christmas Eve also means it’s a low-effort day here at Hackaday, so here’s a few cool things we’ve run across in the past few weeks.

A Round OLED Display

1_13inch_Round_OLED

That right there is a circular OLED display. [ArtistEngineer] over on reddit found this display on AliBaba. It’s a 1.13 inch diameter display with a resolution of 128×128 (yeah, we don’t know either). This looks like a great display for a DIY wrist watch, digital gauge, or loads of other devices where a square display doesn’t make much sense.

There seems to be a few circular OLED display manufacturers – including Truly Semiconductors who happened to put up a datasheet for their round display – but sourcing these in reasonable quantities is a pain. Anyone up for a group buy? Think of the fun you’ll have coding a polar coordinate display!

Computing with transistors

gate

So you know computers are made up of simple logic gates, latches, buffers, and other miscellaneous digital cruft,  but how do we turn these digital circuits into a computer? Over the last few months, [Andrew] has been putting up a bunch of blog posts on the application of digital logic. Start out on the ‘Computing with Transistors’ post before moving on to The Digital State and Circuits and Arithmetic. There’s some good readin’ there.

 Embedding 3D objects in a web page

Go ahead. Click it. It’s Sketchfab that allows anyone to publish interactive 3D designs without a browser plugin. If anyone out there is trying to build a Thingiverse clone that isn’t tied to Makerbot, consider using this for the preview page for each object.

Surprisingly, Twinkies were the one thing that didn’t survive the Apocalypse.

twinkie

While there’s no use in mourning the death of the Twinkie – Little Debbie also makes small cream-filled cakes – you might as well include some Twinkies, Snowballs, Ding Dongs, and Ho-Hos in your Christmas baking. [scoochmaroo] on Instructables put together a list of homebrew recipes for the now defunct Hostess snack cakes.

Perfect for autonomous robots

code

[maxogden] over on the gits put together a script for automatically joining wireless networks on Linux. This was tested on a Raspberry Pi, and we’re thinking it would be perfect for whatever autonomous creation you’ll be building in your workshop next year.

How computers work, starting with transistor gates

[Andrew Gibiansky] has just started a tutorial series called Computing with Transistors. It’s purpose is to pull back the many veiled layers between high level languages and the controlling of electrons. And fittingly this first post starts off by explaining voltage source, load, and current. Don’t be thrown by its simplicity though. [Andrew] quickly moves on to talk about switching transistors and how they are used to build gates like the OR NOR gate seen above.

If this is the least bit interesting you should also look back at the post about Nand 2 Tetris. It’s an online course that works its way through The Elements of Computing Systems text book. We’ve been following that journey ourselves, having made it through the hardware build in about a week. The assembler took about the same amount of time, and right now we’re in debugging hell trying to get the last function call and return parts of the VM translator to work right. We’ve used most of the skills needed in this journey before, but never all in one project. It really has shed a lot of light on the gaps in our knowledge, and we’re having a lot of fun at the same time!

[via Reddit]

Building a computer out of 555 chips

[M. Eric Carr] came up with an interesting build for the 555 contest earlier this year, and we’re pretty sure that it would have kicked the winner of the complex category off the throne if it were completed. Although it’s a few months late, we’re happy to feature at least part of his 555-based computer on Hack A Day.

[Read more...]

Intermediate Concepts: Building discrete transistor gates

[Simon Inns] has put together a lesson in digital logic which shows you how to build your own gates using transistors. The image above is a full-adder that he fabricated, then combined with other full adders to create a 4-bit computer.

Don’t know what a full adder is? That’s exactly what his article is for, and will teach you about binary math and how it is calculated with hardware. There’s probably at least a week’s worth of studying in that one page which has been further distilled into the five-minute video after the break. Although building this hardware yourself is a wonderful way to learn, there’s a lot of room for error. You might consider building these circuits in a simulator program like Atanua, where you can work with logic gate symbols, using virtual buttons and LEDs as the outputs. Once you know what you’re doing with the simulator you’ll have much more confidence to start a physical build like the one [Simon] concocted.

Finding this project a little too advanced? Check out our Beginner Concepts articles to help get you up to speed.

[Read more...]

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