Various Cantenna builds


Here is a classic project used to increase wireless signal strength. Cantennas focus using a waveguide very much like a magnifying glass focuses light. [Robert] made a Natural Light beer cantenna, pictured in the upper left. His approach used three beer cans, a paper towel holder, and a shower curtain rod. On the tipline, he noted a signal boost from 11Mbps to 54Mbps. This is certainly something we can hack together if our room lacks adequate signal. Read about parabolic and seeking versions after the break.

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Battery desulfator


Hack a Day favorite [Mikey Sklar] is back with a new project. Mini-D is a battery desulfator. If a 12V lead-acid battery sits with a voltage below 12.3V, sulfur crystals will begin to form on the lead plates. This crystal growth increases the internal resistance and eventually makes the battery unusable. A battery desulfator sends high frequency pulses through the battery to create a resonance that will break up the crystals. On a 60lb automotive battery, it will take approximately three weeks to completely desulfate. You can find schematics plus a dozen lines of code for the ATmega169 on his site. Embedded below is a video where he explains the device and other techniques like load testing.

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Capacitive discharge cutting

capacitive discharge cutting

Capacitive discharge cutting provides more control than linear transformer versions. A very large capacitor is charged to a precise voltage and then discharged through the material to produce a controlled cut. The same device can also be used for spot and tab welding. A video of copper roof flashing being cut is embedded below. An example of a linear transformer can be found in our our How-to: build your own spot welder.

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EVIC engine


The EVIC is a computer controlled internal combustion engine, utilizing a cam less solenoid actuated valve system. In addition to intake and exhaust valve control, the processor also handles ignition timing. With dynamic valve timing, it is possible to make an engine more efficient. Where a classic combustion engine would wastefully burn fuel, the EVIC can skip power cycles which are not needed. By increasing the valve duration, the CPU enables easy starting. The latest is the EVIC Mk3 which adds an exhaust valve sensor, and 3:1 solenoid leverage. There is a photo gallery with several EVIC engines. The Mk2 Twin is demonstratedĀ in the video embedded below.

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1964 300baud modem surfs the web

[phreakmonkey] got his hands on a great piece of old tech. It’s a 1964 Livermore Data Systems Model A Acoustic Coupler Modem. He recieved it in 1989 and recently decided to see if it would actually work. It took some digging to find a proper D25 adapter and even then the original serial adapter wasn’t working because the oscillator depends on the serial voltage. He dials in and connects at 300baud. Then logs into a remote system and fires up lynx to load Wikipedia. Lucky for [phreakmonkey] they managed to decide on a modulation standard in 1962. It’s still amazing to see this machine working 45 years later. He’d love to hear from you if you’ve used a similar device.

[via Waxy]

Space Invader button


[Marcus] saw [Alex]’s 64 pixel project and decided it could be implemented in even less space. Pictured above is his Space Invader button with a bicolor LED matrix. The controller board is all SMD and piggybacked on the matrix. An ATmega164P drives the 24 pins via transistors. In addition to animation, the board can do LED sensing too. It’s a very clever project and [Marcus] has some notes about working with such tiny components. You can see a video of it below. Continue reading “Space Invader button”

Automated drum


A team of three PhD students constructed this ‘multi-mallet automatic drumming instrument (Madi)‘. Their Expressive Machines Musical Instruments site is dedicated to building instruments like this and they recently showed their work at the first annual Guthman Musical Instrument Competition. A ‘low-stakes X Prize’ for musical instruments. 25 applicants were chosen to show their unique musical instruments for $10K in prizes. We like the team’s Madi because it’s adapting a traditional instrument and then pushing it to the limit. It reminds us of the Crazy J mechatronic guitar from 2005. You can see a video of the Madi playing below.

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