The Cool Kids All File Their Resistors For Accuracy

July 5, 2012 by 43 Comments

Here’s a tip to keep in your back pocket, you can use a metal file to adjust your resistors. [Gareth] shows off this technique in the video after the break. A metal file is literally all that you need to do some fine tuning. Just make sure you’re starting off with a carbon film resistor as this will not work with the metal film variety.

His example shows a 10k resistor which is reading just 9.92k on his multimeter. But he needs precisely 10k. After getting through the protective layer he makes just a couple of passes with a small file, each time adding about 20 Ohms of resistance. Now he does mention that excessive deep cuts can hurt the power rating of the resistor. But this certainly isn’t damaging it if done correctly. It turns out this is how they are tuned at the factory.

One possible use he mentions is trimming the balance on a hacked servo motor.

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Facedancer Board Lets Your Python Programs Pretend To Be USB Hardware

July 5, 2012 by 9 Comments

This is the prototype board for [Travis Goodspeed’s] new USB development tool called the Facedancer. He took on the design with USB security exploits in mind, but we think it’s got a lot of potential for plain old development as well.

Kudos on the [Frank Herbert] reference when naming the project. Like the characters from the Dune mythology that can perfectly mimic any person they touch, this device let’s you mimic whatever you can imagine. One the USB ports connects to the victim (or host) the other connects to a development machine. Python can then be used to send USB commands in real time. Think of this as doing the same thing the Bus Pirate does for SPI and i2c, except that it’s doing it on the USB protocol itself. This way you can feel your way through all of the road-bumps of developing a new device (or testing an exploit) without the need to continually compile and flash your hardware.

Automatic Beverage Delivery System

July 5, 2012 by 19 Comments

Members of theTransistor, a Provo, Utah based Hackerspace, are showing off their entry in the Red Bull Creation contest. This is an all-in-one energy drink delivery system. It can take a warm can of Red Bull from a reserve rack and turn it into a chilled cup of goodness in no time. And it (kind of) cleans up after itself too!

The process starts when a can is opened by lancing it through the side walls. At the upper right corner of the rig you can see the apparatus that is responsible for this beverage extraction technique. The drink drains from the newly created openings into a funnel below. It then enters a heat exchanger the team built by surrounding an aluminum pipe with several copper pipes. The copper has ice water circulating through them from the orange bucket that serves as the reservoir. By the time the drink gets to the cup on the bottom left it is ready to drink. The empty can is crush, falling into a bin and making space for the next in the 16-can backup supply.

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F/stop Printer For Analog Printing Black And White Photos

July 5, 2012 by 3 Comments

This beautifully crafted device is a timer used for getting the perfect exposure when making film prints of photos. But in addition to keeping time, it also does logarithmic calculations that are based on the f-stop values used for each exposure. It does this in 1/100th of a stop increments. While he was at it, [William] also decided to pack in a bunch of other features like dry down correction, and support for making test strips. This is a little hard to understand when discussed in the abstract, but just take a look at his video after the break where [William] walks us through an example exposure and all will become clear.

You can see from the construction page that the device is basically an Arduino shield. It provides a relay for controlling the exposure lamp, a keypad, rotary encoder, and character LCD. Slap it in a fancy case, connect it to the equipment you’re using, and you’ll be creating perfect prints in no time flat!

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Television Built From A Tin Can

July 5, 2012 by 18 Comments

A tin can and string telephone just doesn’t impress the kids anymore. Luckily, now you can  turn that tin can telephone into a television, as [aussie_bloke] over on the Narrow-Bandwidth Television forum showed us.

[aussie_bloke]’s tin can TV is a mechanical television, a TV where the scanning lines of a CRT is replaced with a spinning disk with very small holes.(if you have a better analogy in this day of LCDs, tell us). Instead of the usual Nipkow disk, [aussie_bloke] used a small tin can.

The image displayed on this TV isn’t very large; there are only 30 scan lines and the pattern of the holes results in a display 10.5mm in width by 7.85mm high. Basically, this display is microscopic but it’s still very impressive.

Sure, you may not be able to sit your kids down in front of this can-powered TV and let them watch Yo Gabba Gabba for hours on end, but it’s more than enough to impress those technically minded kids.

You can check out a video of [aussie_bloke]’s can TV after the break. Thanks [gary] for sending this in.

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Raspberry Pi Prototyping Boards Available At Adafruit

July 5, 2012 by 24 Comments

If you’re one of the lucky few with a Raspberry Pi, adafruit has two things you might be interested in if you’re into GPIO hacking.

First up is the Pi Cobbler kit. It’s a 2×13 ribbon cable with a breakout PCB ready to attach to a solderless breadboard; perfect for playing around with (or cobbling together… get it?) the GPIO pins on your Raspi.

Next up is the Pi Plate kit that comes complete with enough perfboard space, screw terminals, and female headers to kill a yak. All the GPIO, I2C, and SPI pins are broken out on the Pi Plate, making it very easy to prototype a semi-permanent Raspi circuit.

They might be just prototyping boards now, but we expect these Pi Plates to quickly evolve into a truly useful device with the addition of a few level shifters, port expanders and a few ADCs and DAC thrown in for good measure. If you’re still on the fence and thinking about buying a Raspi, I ordered one last week from element14 and now have an expected ship date of November 5th. These things must be really popular.

Flimsy Pi Case Still Provides A Level Of Protection

July 5, 2012 by 14 Comments

This flimsy case isn’t going to protect your Raspberry Pi if you knock it off the workbench. It will provide a level of protection against shorting out from contact with metal objects, or from liquids spilled in the near vicinity. [CGPatterson] ended up making this case from a single sheet of transparency film.

The project is basically papercraft. He started with the dimensions published on the Raspberry Pi FAQ, which turned out to be wrong. Not having a caliper available to help with the precision of the measurements, he grabbed his ruler and did the best he could. The first two cases were a poor fit, but as you can see the third is like a glove. Luckily you don’t have to go through this same trial and error as he release the design. Both A4 and US Letter sized PDFs are available for download. Print them out on the transparency, cut along the lines, apply transparent double-sided tape to the tabs and you’re in business. If you wish to alter the design he has also posted the SVG source he made in Inkscape.

This is certainly a good option for those of us without the ability to produce laser cut parts.