High efficiency solar charger circuit tops off those lead-acid batteries

Make your next project solar-powered with this charging circuit. It’s completely through-hole, and there are no microcontrollers that need to be flashed. If you can source parts and are handy with a soldering iron building this will be a breeze.

Both the maximum system voltage and the low voltage drop out are configurable. After assembly, you just need to attach a regulated power supply to the load terminals. Tune the power supply to the max voltage and turn a potentiometer until an LED comes on, then repeat the process for the drop out voltage. Board artwork for the two-sided PCB and a schematic are available from the page linked at the top. If you’re not into etching your own circuit boards you can buy one for around $10.

[Thanks Murray]

The weighted companion cube will never threaten to stab you and, in fact, is a subwoofer

From the techPowerUp! forums comes an awesome weighted companion cube subwoofer built by the metonymical user named [Cube].

This build started off as a coffee table that was to have an oval glass top (no word if the edges were going to be blue or orange). The guts of the cube are taken from a 400 Watt sub. As any good sub builder would, [Cube] kept the air volume and port tuning of the donor box.

We’ve seen a companion cube sub before that featured EL wire for a ‘glowing cube’ effect, but [Cube] may have taken things a little too far by including glowing rings on each side of the cube. The rings lit by 2,500 LEDs mounted on pieces of perspex and wired point-to-point. While [Cube] claims he’s ‘not a electronics guru,’ he certainly has a lot of patience to assemble those lights.

Check out [Cube]’s YouTube build video after the link. Credit to [Todd] for sending this one in.

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Improving your welder without a microcontroller

We’re always impressed when a piece of hardware is torn apart, rebuilt and ends up exceeding the capabilities of the original device. [Dave] and [Will]’s home-built TIG welder is no exception to that rule.

When [Dave] and [Will] started working on converting a simple AC stick welder to a welder with every function imaginable, they decided to keep it simple. After looking at some high-price commercial welders they came up with a list of features they wanted to have and decided to implement this in TTL and CMOS logic. The guys didn’t want to go with a microcontroller solution because not everyone can code, and discrete chips are very easy to troubleshoot given minimal tools.

For the high voltage part of the build, the original flyback transformer was replaced with a neon sign transformer and homebrew spark gap and capacitor. The plans for a homebrew spark gap and cap didn’t quite work out so they were replaced with commercial units. The guys included schematics and a PCB layout (PDF warning) of their build. It’s always great to see an amazing logic chip build, and improving an existing tool never hurts.

Thanks to [Franci] for sending this one in.

Adding Fluke 54 II features to a 51 II thermometer

The difference between Fluke’s 54 II and 51 II thermometers is the addition of a second channel for dual temperature sensing, and buttons which control data logging. Oh, and an additional $150 in price for the higher model. [TiN] was poking around inside and with the help of some forum members he figured out how to unlock additional features on his low-end Fluke temperature meter. You can do the same if you don’t mind cracking open the meter, sourcing and soldering most of the components seen above, cutting holes in the case for the buttons, and hoping it still works when you put everything back together.

It seems that Fluke designed one full-featured unit and watered it down to fill a hole in the lower-priced market just like some other testing-hardware manufacturers (Rigol’s digital storage oscilloscopes come to mind). But the MSP430 P337I in this meter cannot be reflashed, so this would most likely be unhackable hardware if the firmware for the two models is different. After some intensive study of the PCB layout [TiN] found a set of resistors which seemed to serve no external hardware purpose. They do connect to the microcontroller and together they create a two-bit code. He was able to get pictures of the four different hardware models and work out which resistor combinations identify the different meters. Now he can get the firmware to believe it is operating a Fluke 54 II, the rest is just putting the correct passive components onto the unpopulated locations.

We think the quest is what is of interest with this hack. [TiN] did an amazing job of photographing and writing about each step in the process. We’re unlikely to try this ourselves but loved reading about it.

A No-touchscreen Picture Frame?

Many people have touch-screen devices, however, this hack claims to be the first picture frame to feature a “no-touch” interface. Although someone somewhere certainly has a digital picture frame hooked up to a “Clapper”, we’re going to give [Wasabi] the benefit of the doubt.

After buying a Microtouch kit from Adafruit several months ago with the intention of building something meaningful, [Wasabi] ran into a common problem among hackers, a lack of time. Instead of totally giving up on the device, the decision was made to make it into a simple picture frame. Although the Microtouch features a touchscreen, it also features an accelerometer. With a little hacking, as described in his write-up, the “touchless” picture frame was born. Cleverly, the screen was hidden behind glass, but through this interface, interaction was still possible.

The device itself seems like a great hacker tool, especially at a price point of just under $70. Here’s a hack where “Zork” was ported to this device, but be sure to send us any other projects you come up with using it! Check out the video after the break of this device in action!

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Weekly Roundup 9/10/11

In case you missed them, here are the most popular posts from the previous week.

Our most popular post was one of our Engine Hacks about a remote control airplane built by [Bruce Simpson] that has a pulse jet attached to it. It’s noisy and fast! Want to wake up the whole neighborhood, fly one of these around early in the morning.

Next up is this post about an unique window display that [Alex] built which draws onto the glass using a pair of stepper motors and a felt tipped pen. He is using processing and an arduino to control the motors. The end effect is that this device can draw gray scale images.

After that is another one of our Engine Hack posts where we show a lawn mower that has been converted to run on steam. This one is most definitely a hack and seems somewhat dangerous to boot.

This post shows off a working PIP-Boy 3000 created by [MyMagicPudding]. If you are a fan of Fallout, this is one to check out.

Finally, this post shows off a very large 3D printer that can print items as large as 15.8″ x 15.8″ x 12.7″. This is a custom built device and has a very nice writeup showing how it is put together.

Engine Hacks: Build a turbojet from junkyard parts

Turbo chargers from cars are readily available and easily modified, so why not modify a turbo into a jet engine?

While [Mike]’s junkyard jet made the rounds on the Internet over a decade ago, the theory behind the homebrew turbojet is still sound. After pulling a turbo out of a 1983 Nissan Pulsar, [Mike] built a combustion chamber out of 2-inch pipe fittings. The propane fuel is ignited with a simple motorcycle spark plug and produces a hot and powerful blast of air twenty feet from the exhaust.

We suppose [Mike] wasn’t satisfied with such a puny engine made out of junk, so he decided to step it up a notch and improve his engine. After some development, [Mike] managed to build another jet out of a larger turbo that doesn’t require a constant spark. The newer engine produces ‘hurricane force wind’ 10 feet from the exhaust. We’re not sure how much thrust that translates into, but we’re a little surprised this engine hasn’t been mounted to a go-kart yet.

Check out the walk through and demo of the junkyard jet after the break.

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