San Francisco Event: Hardware Developers Didactic Galactic

August 6, 2014 by Mike Szczys 8 Comments

It’s a mouthful to say, but an evening-ful of fun. San Franciscans who like to talk about all things hardware need to block this one out on their calendars:

Hardware Developers Didactic Galactic
Thursday, August 14th 2014 starting 6pm-9:30pm
500 3rd St., Suite 230 in San Francisco

The night will include a few talks on hardware; So far we know [Matt Berggren] is doing FPGA stuff, [Chris Gammell] will talk about KiCAD, and I’m going to talk about the community adventure that is Mooltipass. We’re also looking for others to make presentations so step up and share your hardware passion!

In addition to the formal talks there’ll be plenty of time for chewing the fat with all the other hardware-awesomes that will be there. See you a week from tomorrow, and don’t be shy about bringing your own hardware to show off!

An Excel Based High Frequency Transistor Amplifier Calculator

July 31, 2014 by Mathieu Stephan 6 Comments

[Paulo] just tipped us about an Excel based high frequency transistor amplifier calculator he made. We’re guessing that some of our readers already are familiar with these class A amplifiers, commonly used to amplify small audio signals. Skipping over the fact that their efficiency is quite low — they are cheap to make, don’t require many components and usually are a great way to introduce transistors to new electronics enthusiasts. All you usually need to do is a few calculations to properly set your output signals and you’re good to go.

Things are however more complex when you are amplifying 200MHz+ signals, as all the components (complex) impedances have to be taken into account so you can get a nice amplification system. On a side note, at these frequencies your transmission lines impedances may even vary depending on how much solder and flux you left on your SMT pads along the way. [Paulo]’s calculator will therefore compute most of the characteristics of two class A common emitter/collector amplifiers for specified loads.

Changing Unipolar Steppers To Bipolar

July 29, 2014 by Brian Benchoff 68 Comments

If you’ve been a good little hacker and have been tearing apart old printers like you’re supposed to, you’ve probably run across more than a few stepper motors. These motors come in a variety of flavors, from the four-wire deals you find in 3D printer builds, to motors with five or six wires. Unipolar motors – the ones with more than four wires – are easier to control, but are severely limited in generating torque. Luckily, you can use any unipolar motor as a more efficient bipolar motor with a simple xacto knife modification.

The extra wires in a unipolar motor are taps for each of the coils. Simply ignoring these wires and using the two coils independently makes the motor more efficient at generating torque.

[Jangeox] did a little experiment in taking a unipolar motor, cutting the trace to the coil taps, and measuring the before and after torque. The results are impressive: as a unipolar motor, the motor has about 380 gcm of torque. In bipolar mode, the same motor has 800 gcm of torque. You can check that video out below.

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An Automated Flappy Bird Player

July 27, 2014 by Brian Benchoff 30 Comments

game Flappy Bird has been ported to just about every system imaginable, including but not limited to the Apple II, Commodores, pretty much every version of the Atari, and serves as a really great demonstration of the TI-99’s graphics capabilities. Porting is one thing, but having a computer automate Flappy Bird is another thing entirely. [Ankur], [Sai], and [Ackerly] in [Dr. Bruce Land]’s advanced microcontroller design class at Cornell have done just that. They’re playing Flappy Bird with a camera, FPGA, and a penny wired up to a GPIO pin to guide the little 8-bit-bird through Mario pipes.

The setup the team is using consists of a webcam that records the screen of a smartphone, an FPGA, and a little bit of circuitry to emulate screen taps. Inside the FPGA, the team is looking at the video stream from the phone to detect the bird, pipes, and gaps. The ‘tapper’ unit is a US penny, placed right above the ‘tap’ button, wired to a GPIO port. This was found to be the ideal contact for a capacitive touch screen – taps that were too small weren’t registered, and taps that were too big registered as two taps.

For spending an entire semester on automating Flappy Bird, the team has a lot of knowledge to show for it, but not the high score: the bird only makes it through the first pipe 10% of the time, and the second pipe 1% of the time. The high score is three. That’s alright – getting the algorithm right to play the game correctly was very, very difficult, and to nail that problem down, they estimate it would take at least another semester.

A Router-Based Dev Board That Isn’t A Router

July 27, 2014 by Brian Benchoff 44 Comments

Here’s somethi router ng that be of interest to anyone looking to hack up a router for their own connected project or IoT implementation: hardware based on a fairly standard router, loaded up with OpenWRT, with a ton of I/O to connect to anything.

It’s called the DPT Board, and it’s basically an hugely improved version of the off-the-shelf routers you can pick up through the usual channels. On board are 20 GPIOs, USB host, 16MB Flash, 64MB RAM, two Ethernet ports, on-board 802.11n and a USB host port. This small system on board is pre-installed with OpenWRT, making it relatively easy to connect this small router-like device to LED strips, sensors, or whatever other project you have in mind.

The board was designed by [Daan Pape], and he’s also working on something he calls breakoutserver There’s a uHTTP server written specifically for the board that allows any Internet connected device to control everything on the board. There’s also an HTML5 app they’re developing which could be pretty interesting.

All in all, it’s a pretty cool little device that fits nicely in between the relatively simplistic ‘Arduino with an Ethernet shield’ and a Raspi or BeagleBone.

Using Surface Mount Devices On A Breadboard

July 25, 2014 by Brian Benchoff 17 Comments

[Czar] was working on a project with the Raspberry Pi using the MCP3008 analog to digital converter. The surface mount SOIC version of this chip was slightly cheaper, and there’s always a way to make that work (Portuguese, Google Translation). How [Czar] did it is fairly impressive, as it’s a bit more flexible for breadboard designs than a through-hole version, and done correctly, is an extremely sturdy hack.

A few new leads needed to be soldered onto the SOIC package, and for this [Czar] chose jumper wires. This makes each pin easy to plug into a solderless breadboard, and since [Czar] was extremely clever, all the wires for power, ground, analog, and SPI are color coded.

Simply soldering a few jumper wires onto a chip won’t last for very long. To solve this problem, [Czar] potted the entire chip and its connections with hot glue. Probably not the best solution, and a heavy-duty epoxy would have been better, but the current build is more than enough to stand up to the relatively minor abuse it will receive on the workbench.