Battery Basics – Choosing a Battery for Your Project

If choosing a rechargeable battery for your project intimidates you, [Afroman] has prepared a primer video that should put you at ease. In this tutorial for battery basics he not only walks you through a choice of 5 rechargeable chemistries and their respective tradeoffs, but gives a procedure that will allow you to navigate through the specs of real-world batteries for sale – something that can be the most intimidating part of the process.

You cannot learn everything about batteries in 9 minutes, but watching this should get you from zero to the important 80% of the way there. Even if your project does not give you the specs you need to begin buying, [Afroman] tells you what to measure and how to shop for it. In particular, the information he gives is framed in the context you care about, hopefully ensuring you are not waylaid by all the details that were safe to ignore. If this is not enough, [Afroman]’s prequel video on battery terminology has more detail.

Much like your high school English teacher told you, you need to know the rules before you can choose to break them. Many of battery absolute Dos or Don’ts are written for the manufacturer, who provides for the consumer, not the hacker. Hackaday has published hundreds of battery articles over the years; search our archives when you are ready for more.

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Goodbye Hackaday subdomains

subdomains-going-away

We’re sure some of you will be sad that the LIFE and HANDMADE Hackaday subdomains are going away. Others will be happy, and many won’t realize they even existed.

We tried a little experiment in diversity this summer, launching the two outliers of our main focus (which is engineering oriented hacks). Each was interesting in their own way, with steady streams of readers and small conversations. But this diverted some of the attention away from what we do best, and that’s why we’re closing them down.

Handmade has already been absorbed. The features which highlighted craftsmanship and artful creations like blowing glass are tangentially interesting. We’ve imported all of the articles and will continue to feature this sort of content from time to time if it fits in with what our readers are normally after.

Life was a little bit outside of what we normally focus on. These sorts of hacks are interesting tidbits to have bouncing around your brain. But you probably won’t see them hitting our front page. Don’t let that discourage you though. If you’ve got a tip or trick to make daily life less mundane you can always let us know on the tips line. At worst we will ignore you. But you might end up seeing it in a Links post, which is our weekly Sunday column that showcases things which weren’t compelling enough for their own post.

Just to be clear for those that are really paying attention. We’re not cramming this content onto the front page with everything else. We’re phasing it out except for those things that go hand in hand with our lust for tech hacks of the highest caliber.

Reboot Life in a heartbeat

This hoodie senses your heartbeat and uses it to control Life. Conway’s Game of Life, popular in all kinds of electronics projects, uses a grid of cells coupled with a set of rules to mimic the life and death of simple organisms. This iteration displays the game over your own heart, then taps into your heart rate, resetting the game at the beginning of each cardiac cycle. We guess you could say that Life goes on only if you do not.

The EKG circuit that detects the heartbeat is made up of an IR transmitter shining through the tip of your finger to a receiver. An ATmega168 running the Arduino bootloader controls the EKG circuit and resets an ATmega48 which is responsible for Life. [Joe] admits that this is overkill but he’s currently without an AVR programmer; he went this route to make it work. The stylishly-geeky hoodie is taken for a test run (er… test-hop?) after the break.

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Peggy-zilla

peggyzilla (Custom)

For some, a peggy 2.0 is pretty cool, but simply not impressive enough. [MonsieurBon] felt this way and simply built a larger LED rig for his peggy2.0.  It still uses the brains of the peggy, but the LED array is a custom built cabinet, using ping pong balls as diffusers. Another interesting modification is that they added a midi port to the setup to generate music based on what LEDs are lit. They say it creates some nice background generative music during the game of life. You can see a video of the system in action after the break.

It looks like they weren’t the only ones with this idea. The u:moon project is very similar, meant to be hung from a balloon. There seems to be an issue with the gallery on his page though, so you might want to go to his picasa gallery.

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LED Life and Charlieplexing


Yesterday, we featured [Andrew]’s orientation aware camera. We want to highlight another one of his projects: LED Life. It’s a 6×5 LED matrix playing Conway’s Game of Life. He used the low power MSP430 like our e-paper clock. The best part of the writeup is his explanation of how Charlieplexing works. Microcontroller GPIO pins generally have three possible states: output high, output low, and input. This combined with the directional nature LEDs and some creative wiring means you can run a large matrix of individually addressable LEDs with just a few IO pins. Instead of just flipping the IO pins on and off you change their assigned state. Have a look at [Andrew]’s site for some great illustrations of how the system works. A video of his LED Life board is embedded below. Continue reading “LED Life and Charlieplexing”

SMD soldering practice kit


Here’s an interesting kit put together just to help you work on your SMD soldering skills. It’s got 49 SMD LEDs on the front with a programming header and switch jumper. The back has an ATtiny26L and a coin cell. At only 3V, power management is essential; all of the example programs are only addressing one LED at a time (imperceptible to the human eye). If you turn on too many LEDs at the same time, the voltage drop could cause the AVR to reset. Included example programs are a scrolling marque, bouncing balls, and Conway’s game of life. SparkFun has tutorials for regular SMD soldering and using a reflow skillet. The video below shows the kit builder attaching just one LED using the heat and slide method.

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Build a lifeform for io9


Whether you consider yourself a bona fide mad scientist or you simply think your horrifying mutant creations are misunderstood, you’ll want to enter io9’s Build a Lifeform contest.

The contest doesn’t require any actual primordial soup, just a concept of a synthetic lifeform you think would be useful or interesting. There are two categories with different prizes for each one. The first category asks contestants to use the BioBricks registry of standard biological parts to design a lifeform that could be created in a lab. Descriptions of how it would be made, what it would do, and potential hazards in creating it must all be included with the entry. The winner of this category will recieve an all-expenses-paid trip to the Synthetic Biology Conference in Hong Kong in October.

The second category is more focused on creativity, asking for the same descriptions as the first category without any BioBricks data. While this is the more speculative category, proposed lifeforms must still be plausible to create using current technology. The prize is $1000 and a signed drawing of your lifeform rendered by “a cool comic book artist.”

Both categories offer pretty good loot for your concepts, just be sure they’re more original than an esquilax if you intend to win.

For the background on BioBricks, check out [Drew Endy]’s Hacking DNA talk from last year. He’s one of the judges for the contest.