4-bit Adder Built From Mechanical Relays

April 26, 2014 by 20 Comments

relay-adder-register-memory

Would you consider this to be doing math the old-fashioned way? Instead of going with silicon-based switching (ie: transistors) this 4-bit adder uses mechanical relays. We like it for its mess of wires (don’t miss the “assembly” page which is arguably the juiciest part of the project). We like it for the neat and tidy finished product. And we like it for the clicky-goodness which surely must bloom from its operation; but alas, we didn’t find a video to stand as testament to this hypothesis.

The larger of the two images seen above is from the register memory stage of the build. The black relay in the bottom right is joined by a ring of siblings that are added around the perimeter of the larger relays before the entire thing is planted in the project box.

Sure, simulators are a great way to understand building blocks of logic structures like an adder. But there’s no better way to fully grip the abstraction of silicon logic than to build one from scratch. Still hovering on our list of “someday” projects is this wooden adder.

[Thanks Alex]

 

Sink Your Teeth Into PiPhone

April 26, 2014 by 37 Comments

Raspberry Pi cell phoneHave you ever dreamed of independence from smartphone bloatware? If you have a Raspberry Pi and an Adafruit TFT, you’re halfway to making your own version of [Dave]’s PiPhone.

This tasty proof-of-concept cellular sandwich is made by adding a Sim900 GSM/GPRS module, which communicates via UART, to the Pi/TFT hardware while using a piece of foam core board in the middle to prevent shorts. You won’t get free service or anything, but you can pop a pre-paid SIM card into it. He’s powering it with a LiPo battery and using a DC-to-DC converter to set up the 3.7V to 5V. You could do a lot worse than the $158 BOM, and we’re betting you have a Pi lying around already. We wish more phones had baby rocker switches.

There’s a slight problem with the PiPhone: it gets pretty warm and there isn’t a lot of room for air circulation. For best results, let it cool on a well-attended windowsill or operate it near a fan like [Dave] did. He doesn’t have the code up on GitHub as of this writing, but he will capitulate to high demand. Make the jump to see [Dave]’s tour of the PiPhone and watch him make a call with it.

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Small-Scale Projects Use Snail-Mail Mail-Scale

April 26, 2014 by 12 Comments

stamps.com scale

Stamps.com offers a free USB scale when you sign up for their service. The first versions of this scale did not have a display. In order to find the weight of an object the scale had to be connected to a computer running the stamps.com software. If you happen to have one of these old scales or are able to pick one up cheap, you may be interested in using it outside of the stamps.com service. There are several options on how to do that.

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The Arduino Operating System

April 26, 2014 by 19 Comments

WGPIOhile Arduino and its libraries are the quickest way to interface with a sensor and blink an LED, sometimes you shouldn’t have to write and compile code to do something exceptionally simple. [Oliver] realized most of the overly simple functions of a microcontroller could be done from a command line running on that microcontroller and came up with the MiniPirate, the Arduino command line tool.

The MiniPirate is just a sketch compiled on the Arduino that allows pins to be set high or low, set a PWM value, or reading and writing I2C bytes. It’s basically an extremely slimmed down version of the Bus Pirate meant for extremely simple modifications of circuits and peripherals.

[Oliver] demos his MiniPirate by taking a DS1307 real-time clock, wiring up the I2C bus, and writing values to set the time. It’s a very simple implementation meaning he needs to write everything in hex, but it’s still easy enough to find a use in many other projects.

Sci-Fi Contest Roundup: Thinking 4th Dimensionally

April 26, 2014 by 14 Comments

Notwithstanding [John Titor] and his time travelling ’67 Corvette convertible, the coolest time machine on wheels has to be the DeLorean from Back to the Future. BTTF is apparently a very popular theme for our sci-fi contest, with a lot of great entries.

You mean to tell me  you made a time machine? Out of a Hyundai Accent?

fluxAfter a careful bit of research, it appears the Hyundai Accent (GLS) has both a higher top speed and faster 0-60 time than a DeLorean, and that’s before the installation of time circuits, a flux capacitor, and plutonium reactor. [docbrownjr] and [Jennifer] decided their Accent was the perfect vehicle for a time machine conversion and decided to add a Mr. Fusion  to the mix.

Like the on-screen version, this version of a Mr. Fusion is made from a kitchen appliance. With the original Krups coffee grinder out of production, the team settled on an iced tea machine. There will, however, be copious amounts of dry ice involved,  as will half-empty beer cans and banana peels.

WiFi-enabled Flux Capacitor

ledAfter knocking his head on a toilet, [Beamsjr] came up with a great idea – a networked flux capacitor, able to display the Teamcity build progress.

This build is going all out with custom PCBs – one for the controller board, and three for the shift registered LEDs underneath the acrylic knobbies in the flux capacitor. WiFi is provided by the TI CC3000 module, with the main microcontroller being an ATmega 328p,

Time circuits on

segmentsHonestly, we’d be a bit disappointed if this contest didn’t have a BTTF time circuit build entry. Luckily for us, [atheros] and [bwa] are on top of things with their time circuit clock, complete with an alarm and FM radio receiver (FM isn’t going to work in 1955, guys).

Unlike a few other time circuit builds we’ve seen over the years, the guys are doing this one up right, with 14-segment LEDs for the month display. They’re etching their own boards for this one, and it’s looking like it’ll be a very cool project when it’s complete.

A H-Bridge Motor Controller Tutorial Makes It Simple To Understand

April 25, 2014 by 13 Comments

hbridge tutorial

[Afroninja] is back with another great tutorial on basic electronics. This time around he’s explaining H-Bridge motor controllers and how they work!

Even if you don’t have much (or any) experience with basic electrical circuits, [Afroninja] explains the concept of an H-Bridge motor controller in a clear, concise and easy way to understand. So what’s an H-Bridge anyway? For any project using DC motors, if you want to be able to spin up the motor in either direction, you’re going to need a method to power the motor in two different configurations, i.e. you’re going to have to swap the polarity some how.

The easiest way of doing this is with an H-Bridge. It’s called an H-Bridge… because it’s shaped like an H, with the motor in the very middle. It allows both polarities to control the motor — however if you do it with just plain old switches or relays, you could short the circuit if you try going in both directions at once! To solve this, [Afroninja] explains how to poka-yoke (Japanese term for Idiot-Proof) the circuit, by using transistors which will sink the voltage if you try to abuse the circuit.

It’s a 5 minute video and well worth the watch — stick around after the break to learn more!

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NES Cartridge Hack Makes Great Novelty Gift

April 25, 2014 by 13 Comments

NES cartridge with arduino

Most all of us recall the Blinking Screen of Death on original NES systems. This was caused by a bad connection between the cartridge and the NES cartridge connector. For whatever reason, it became a very popular idea to give a quick blow down the cartridge, even though this didn’t really help. [Dale] decided to play on this annoying problem by making the NES Blow Cart!

Inspired by a previous cartridge hack, [Dale] mounted a custom made circuit sporting the ever popular ATtiny85 in a Super Mario / Duck Hunt cartridge. A small microphone sits where the original cartridge connector was, along with the on/off switch and program header. A quick blow triggers the ATtiny85 to play a song.

The most difficult part for [Dale] was to figure out how to get the ATtiny to play “music”. This was solved with the discovery of a library called Rtttl. This allowed him to take old Nokia Super Mario and Zelda ringtones and get them on the Attiny85. All files, including the rtttl library are available on his github. Be sure to stick around after the break for a video of the project in action.

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