Misc Hacks

4173 Articles

Doubling Down On Motor Drivers

August 30, 2012 by 31 Comments

Motor driver chip too weak for your needs? Just use two of them. That’s the advice which [Starlino] gives. He stacks motor driver chips to product move powerful controllers.

When stacked as shown, the driver combos should be able to drive at 4A. This is partly because he ganged together the outputs in pairs, and also because of the stacking. That’s a lot of juice, but [Starlino] documented his testing stage which shows that they’re up to it. It’s a bit hard to see from this angle, but he is using a serpentine heat sink. It snakes its way between the stack of chips, then over the top chip before folding back and spreading its wings. The motors he’s using have a stall current of 3.7A, and he included resettable fuses graded at a 2A hold current. He’ll be glad to have that extra protection is something goes wrong with the drivers.

[Thanks Roger]

Gilded Hello Kitty Ax Made Using Electrolysis

August 29, 2012 by 36 Comments

Ummm…. cute? For the Hello Kitty fan who has everything?

Yeah, we’re really not sure what’s going on here. It’s an art piece on which [Denis] spent a lot of time. He polished it, etched it, painted it, applied gold leaf, and drilled a hole for a charm. It’s that hole which interested us the most. He had a heck of a time figuring out how to make a hole in the hardened steel. The solution that finally worked was to use electrolysis to bore through the metal (translated).

[Denis] first made a small depression where he wanted the hole. This took time, and pretty much ate through the engraver bit he was using. But it was just enough to hold a drop of saline. He connected the positive side of his power supply to the ax head, then dipped the negative lead into the drop of saline. Each time the drop turned black he wiped it away and replaced it with fresh solution. Just five hours of this and a pack or two of cotton swabs and he was through.

Build Your Own Forge Inside A Gallon Paint Can

August 27, 2012 by 14 Comments

If you’d like to try your hand with the art of Blacksmithing but don’t want to go all-in on your first project this may be for you. It’s a forge which you can build for under $100. [Mike O’s] creation has some great features, like the option of using the forge as a pass through, and he finds it’s possible to heat metal up to 4″ wide.

He bought an empty paint can at the home store (we guess you don’t want fumes from any paint residue). The business end of the forge is actually the bottom of the paint can. He cut a small opening, then lined the inside of the can with Insulwool, a fabric used as heat shielding. From there the inside was lined with several layers of Satanite Refractory Cement. The same applications were made to the paint can’s original lid, which serves as the back of the forge. This way it can be removed for that pass-through we mentioned earlier.

A propane torch brings the heat for this project. [Mike] mentions that you’re going to want to do the first few firings outside as the cement really stinks until it’s been through a few heating cycles. This creation should get him started but we bet he’ll upgrade to something like this coal forge before long.

[via Reddit]

Measuring The Speed Of Sound With Science And Statistics

August 27, 2012 by 22 Comments

Despite what you may have heard elsewhere, science isn’t just reading [Neil deGrasse Tyson]’s Twitter account or an epistemology predicated on the non-existence of god. No, science requires much more work watching Cosmos, as evidenced by [Ast]’s adventures in analyzing data to measure the speed of sound with a microcontroller.

After [Ast] built a time to digital converter – basically an oversized stopwatch with microsecond resolution – he needed a project to show off what his TDC could do. The speed of sound seemed like a reasonable thing to measure, so [Ast] connected a pair of microphones and amplifiers to his gigantic stopwatch. After separating the microphones by a measured distance; [Ast] clapped his hands, recorded the time of flight for the sound between the two microphones, and repeated the test.

When the testing was finished, [Ast] had a set of data that recorded the time it took the sound of a hand clap to travel between each microphone. A simple linear regression (with some unit conversions), showed the speed of sound to be 345 +/- 25 meters per second, a 7% margin of error.

A 7% margin of error isn’t great, so [Ast] decided to bring out Numpy to analyze the data. In the first analysis, each data point was treated with equal weight, meaning an outlier in the data will create huge errors. By calculating the standard deviation of each distance measurement the error is reduced and the speed of sound becomes 331 +/- 14 m/s.

This result was better, but there were still a few extraneous data points. [Ast] chalked these up to echos and room vibrations and after careful consideration, threw these data points out. The final result? 343 +/- 9 meters per second, or an error of 2.6%.

A lot of work for something you can just look up on Wikipedia? Yeah, but that’s not science, is it?

Coin-based Rube Goldberg Helps Bring In Donations

August 21, 2012 by 6 Comments

This kiosk was conceived as an interactive poster to help raise donations for a German relief organization. Instead of just providing a coin jar, the piece puts on a little show of transporting a two-Euro coin from the slot at the top to the repository in the base. Along the way many of the parts move, telling a story in that Rube Goldberg sort of way.

What is surprising to us is how much this looks like one of our own projects — at least up to the point that the display is painted. The link above shows off some pictures from the development stages. The prototype shapes up on an oddly shaped scrap of plywood with the coin’s path plotted out. After the particulars of a trip from point A to point B were established the empty spaces were filled in to add visual interest. If you take a gander at the back of the plywood you get an eyeful of protoboard and draped wires. A camera, Mac Mini, and Dropbox were included in the mix to share an image of the donor on the group’s Facebook page (with the donor’s consent of course).

The piece had a month-long home in the Hamburg airport earlier this year. See what that looked like in the video clip after the break.

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Retrotechtacular: 1983’s Answer To Information Overload

August 21, 2012 by 37 Comments

We can’t say we ever really thought that the problem with the early 1980’s was too much information in the hands of the people. But this promotional video for the Sceptre Videotex Terminal claims that it is the solution to the information overload of the time. The entire video is embedded after the break.

You use your TV as a display, connecting the hardware to a phone line and using a keyboard for navigation. Perhaps our favorite bit is when the announcer informs us that the secret behind the system is its “vast sources of information”. These include the Miami Herald, the Associated Press, the Wall Street Journal, and Consumer Reports. Just remember that at the time you’d need to hit the local library to access all of those resources. Also, searching them wasn’t a possibility.

But wait, this wasn’t just conceived for news. The system — which was backed by Night-Ridder (a huge Newspaper conglomerate) and AT&T — boasted commerce and banking abilities as well as education services. It’s the vision of the Internet which Ma Bell would have preferred to be in place today.

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