555 Timer-based Charge Controller

February 24, 2011 by Mike Nathan 13 Comments

555_charging_controller_circuit

Several years ago [Michael Davis] built a charge controller for his wind turbine and published his construction plans online. This build became quite popular, especially among people that live in remote regions. He states that he is flooded with email each day with questions about his charge controller from people trying to troubleshoot its construction or from people who are unable to source the proper parts.

In order to make things easier for people, he decided to revisit his controller design to see what could be improved, and more importantly, what could be removed. The revision was shelved for awhile, but while in the process of working on another project, he realized that most of his original circuit could be easily replaced with a 555 timer. Since the 555 chip is so ubiquitous, he figured it was a fantastic way to simplify his charger, even if he wasn’t using the chip in the manner for which it was originally designed.

He continued revising his charger, sourcing very basic components and simplifying the circuitry enough that even he was able to build it correctly the first time around. Needless to say, this charging circuit will be his entry in the 555 Design Contest.

Be sure to keep reading for a quick video of his charger in action.

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Reverse Engineering A Mobile Phone E-paper Display

February 24, 2011 by Mike Nathan 6 Comments

msp430_epaper_display

While e-paper is common among e-readers, there are very few, if any phones other than the MOTOFONE that exclusively use an e-paper display. [Steve] had one of these phones sitting around and thought it could be used to build a low-power clock. Since the bistable e-paper display can retain the currently active content even when power is removed, he would only need to update the clock once a minute, when the time changed.

Unfortunately for him, very little publicly-available documentation exists for the display controller Motorola used. To get an idea of how the display was driven, he had to sniff the SPI communications between the processor and the display. Once he had the basic commands down, he spent quite a bit of time figuring out how to activate the different segments of the display, due to what seems to be a rushed design process on Motorola’s part.

Now that [Steve] had reverse-engineered just about everything, he connected the phone to a TI MSP430 to drive the display. He programmed the LaunchPad to serve as a basic clock with great results, as you can see in the video below.

If your interest in e-paper hacking has been piqued, be sure to check out our previous e-paper coverage here.

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Self-regulating Water Heater

February 23, 2011 by Mike Nathan 74 Comments

netduino_controlled_energy_saving_water_heater

Most everyone is looking to live a little greener these days, with motivating factors typically being the preservation of the environment or financial considerations. [Fabien] fit into the latter category after realizing that about 25% of his monthly gas bill went to heating the water he and his family use each day. After a few calculations, he found that they only required hot water 68 of the 168 hours per week that the water heater was typically running. He figured the best way to save a few dollars was to rig the water heater to turn itself down when it wasn’t being used.

He connected a servo to the temperature control knob on his water heater, allowing it to be adjusted by a microcontroller. Having a rough idea as to the schedule his family keeps during an average week, he wrote an application for his Netduino that would actuate the servo when needed. A DS1307 real-time clock was wired to the Netduino for accurate timekeeping, so as to ensure [Fabien’s] wife never had to endure a cold shower.

It’s a shame that most water heaters don’t ship with some sort of programmable thermostat like you see with newer HVAC systems, but this hack is definitely a step in the right direction.

Continue reading to see his power-saving water heater in action.

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Kindle 3.1 Jailbreak

February 23, 2011 by Mike Nathan 15 Comments

kindle_3_1_jailbreak

In the constant battle of manufacturers vs. jailbreakers, the turnaround time between a new software release and a new jailbreak seems to be getting shorter and shorter. [Yifan] noticed that a recent Kindle update broke a previous method of running unsigned code and started the search for a new workaround.

He eventually found a way to force the Kindle to run unsigned code based upon how the software update checked for digitally signed files. With that knowledge in hand, he discovered that he could trick the updater to run any file he wanted by exploiting the standard functionality found in the Unix ‘cat’ command.

On his site, [Yifan] provides more details, source code, and a compiled update file that performs the jailbreak for you. Much like the previous jailbreaks we have featured, it is perfectly legal to do, but you do risk voiding your warranty during the process.

[Picture via Amazon.com]

Building A Dead Mouse’s Switch

February 23, 2011 by Mike Nathan 40 Comments

building_a_better_mousetrap

[Ned] had a mouse problem in a very uncomfortable place.

No, not like the back of a Volkswagen, in his ceiling. He wanted to put a mouse trap up there to take care of the critter, but knowing how nasty a tripped trap can be after a few days, he was hesitant. He recalled a project he saw online where a mouse trap was wired like a dead man’s switch and he got to work putting together a trap of his own.

He scavenged some parts from around the house and wired up the mouse trap so that a pair of LEDs were lit so long as the trap had not been sprung on an unsuspecting mouse. Once a mouse is caught in the trap, his circuit is broken, and the LEDs go off, letting [Ned] know it’s time to poke his head back up into the ceiling and clean things up.

While his trap is decidedly low-tech, we always enjoy seeing a cheap and easy solution to annoying, everyday problems.

Easy DIY Stroboscope

February 23, 2011 by Mike Nathan 12 Comments

stroboscope_output

Looking for something to do in his downtime, [Mista Sparkle] decided that building a simple stroboscope was in order. He already had a set of six LEDs connected to his Arduino from a previous project, so he added a potentiometer to control the rate at which the LEDs flashed, and dug into the IDE.

During his build he discovered that using the Arduino millis() function at high speeds provides terrible resolution, while using the micros() function exclusively limits his low end measuring capabilities. He desired a better range of measurement, so his program was broken into main functions: One which measures the LED flashing frequency in milliseconds and another that measures the LED flashing frequency in microseconds. This allowed him to gauge rotational frequencies from 577 to 30,000 RPM.

[Mista Sparkle] admits that he is not yet well-versed in driving displays with the Arduino, so he views his readings over a serial connection on his PC. Hopefully we’ll see an updated version with those features in the near future.

MIDI Controller Fit For An Arcade

February 23, 2011 by Mike Nathan 6 Comments

arcade_midi_controller

MIDI controllers can be relatively expensive depending on feature sets and requirements, so Instructables user [fraganator] went about building one on his own for just under $100. He originally wanted to replicate a commercially available MIDI controller, which used arcade buttons in lieu of the more common rubberized buttons, since they are large and have a better feel when pressed. Once he drew up plans for his MIDI clone, he realized he wanted more features in his controller than were available in the commercial version, so he started revising.

His final plan included three rows of four arcade buttons as well as four rotary and two sliding potentiometers. All of the components were mounted in a small keyboard enclosure, then wired to an Arduino clone, which manages all of the controller’s functions. The controller is connected to a PC via USB and can perform any number of operations once the buttons are mapped in MIDI-compatible software.

There are no videos of the controller in action just yet, though [fraganator] says one is forthcoming.