Measure Laser Wavelength With A CD And A Tape Measure

March 20, 2015 by Mike Szczys 13 Comments

Obviously the wavelength of a laser can’t be measured with a scale as large as that of a carpenter’s tape measure. At least not directly and that’s where a Compact Disc comes in. [Styropyro] uses a CD as a diffraction grating which results in an optical pattern large enough to measure.

A diffraction grating splits a beam of light up into multiple beams whose position is determined by both the wavelength of the light and the properties of the grating. Since we don’t know the properties of the grating (the CD) to start, [Styropyro] uses a green laser as reference. This works for a couple of reasons; the green laser’s properties don’t change with heat and it’s wavelength is already known.

It’s all about the triangles. Well, really it’s all about the math and the math is all about the triangles. For those that don’t rock out on special characters [Styropyro] does a great job of not only explaining what each symbol stands for, but applying it (on camera in video below) to the control experiment. Measure the sides of the triangle, then use simple trigonometry to determine the slit distance of the CD. This was the one missing datum that he turns around and uses to measure and determine his unknown laser wavelength.

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The Oldland CPU 32-bit FPGA Core

March 20, 2015 by Eric Evenchick 5 Comments

Field Programmable Gate Arrays (FPGAs) let you program any logic you’d like onto a chip. You write your logic using a hardware description language, then flash it to the FPGA. You can even design your own processor and flash it to the chip.

That’s exactly what [jamieiles] has done with the Oldland CPU. It’s an open source 32 bit CPU core that you can synthesize for use on an FPGA. Not only can you browse through all the Verilog code in the Github repo, but there’s also a bunch of tools for working with this CPU core.

Included with the package is oldland-rtlsim, which lets you simulate the processor on a PC. The oldland-debug tool lets you connect to the processor for programming and debugging over JTAG. Finally, there’s a GNU toolchain port that lets you build C code for the device.

Going one step futher, [jamieiles] built a full SoC around the Oldland core. This has SPI, UART, timers, and more features you’d expect to find in a microcontroller. It can be flashed to the relatively cheap Terasic DE0-Nano board.

[jamieiles] has also ported u-boot to the processor, and the next thing on the list is the Linux kernel. If you’ve ever been interested in how CPUs actually work, this is a neat project to look through. If you want more open source CPU cores, check out OpenCores.

The Midwest RepRap Festival – Awesome Stuff In The Middle Of Nowhere

March 20, 2015 by Brian Benchoff 11 Comments

It’s time once again to venture out to Goshen, Indiana for the Midwest RepRap Festival. It is the largest 3D printing con in the entire world where no one is trying to sell you anything. With a qualifier like that, it doesn’t have to be very big, but last year over 1,500 people showed up to the Elkhart county farm show complex and this year many more people are expected.

On the list of attendees is Taulman 3D, makers of fine, odd filament, Lulzbot, [Johnny] of Ultimachine, creator of the RAMBo board, MakerJuice, the FirePick Delta – the most skulled project on hackaday.io, and dozens of other people who make a living with 3D printing.

Of the expected attendees that are not specifically involved with 3D printing, I’m told [Ben Heck] will be there, along with someone from Adafruit and Make. The EFF might have a booth. A local radio station is doing a remote, and the servers at Wings, Etc. — one of the few area pubs — are going to clean up this weekend.

The event officially starts at 4:00pm today, Friday, March 20th. If you won’t be going the entire weekend, I’d suggest showing up on Saturday or Sunday. There will be far too many people there, and I’m slightly agoraphobic. We’ll be posting updates from the MRRF later on.

Hacklet 39: The Kerbal Way Of Doing Things

March 20, 2015 by Brian Benchoff 11 Comments

Kerbal Space Program is a space flight simulator based on an extremely stupid race of green space frogs that have decided to dedicate all their resources towards the exploration of space. It is a great game, a better space simulator than just about anything except for Orbiter, and the game is extremely moddable. For this edition of the Hacklet, we’re going to be taking a look at some of the mods for KSP you can find over on hackaday.io.

Like most hardware builds for Kerbal Space Program, [lawnmowerlatte] is using a few user-made plugins for KAPCOM, a hardware controller and display for KSP. The Telemachus plugin is used to pull data from the game and display that data on a few screens [lawnmower] had sitting around.

There are a few very cool features planned for this build including seven-segment displays, a throttle handle, and neat enclosure.

[Gabriel] is working on a similar build for KSP. Like the KAPCOM, this one uses the Telemachus plugin, but this one adds three eight-digit, SPI-controlled, seven-segment displays, relegendable buttons, and a Kerbal-insipired frame made out of Meccano.

[Lukas]’ KSP Control Panel is another complicated control system that breaks immersion slightly less than a keyboard. He’s using a Raspberry Pi to talk to the Telemachus server to control every aspect of the craft. From staging to opening up the solar panels, it’s all right there in [Lukas]’ control panel.

You may have noticed a theme with these builds; all of them use the Telemachus plugin for KSP. Even though it’s fairly simple to create plugins for Unity, there really aren’t that many KSP plugins build for these immersive control panels and space flight simulators. Or rather, Telemachus is ‘good enough’. We’d like to see a fully controllable KSP command pod model, just like those guys with 737 flight simulators in their garage. If you have any idea how that could happen, leave a note in the comments.

Uber-Cheap FPV Snow Sled

March 20, 2015 by Rich Bremer 15 Comments

Has the winter blues got you RC vehicle guys down? Well, cheer up! Spring is just around the corner. In the meantime though, you can take a page out of [BenNBuilds’] book and build an FPV Snow Sled.

So how is using this Snow Sled in the winter different from any other RC vehicle? [BenNBuilds] controls it from inside his house where he stays warm and toasty. The on-board FPV camera sends video back to a receiver in the house where it can be either displayed on an LCD screen or on FPV goggles. Plus, being able to see the sled from the window doesn’t hurt either when getting in a sticky situation!

The craft it self was made on the cheap from spare parts that were kicking around. The frame is made from foam board and is powered by a ducted electric fan. A rudder similar to that of a hovercraft or swamp boat provides the steering. Since [BenNBuilds’] transmitter had a couple extra channels, he hooked up a pan and tilt system for his FPV camera. Check out the video of this puppy in action after the break….

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Exposing Private Facebook Photos With A Malicious App

March 20, 2015 by Rick Osgood 21 Comments

[Laxman] is back again with another hack related to Facebook photos. This hack revolves around the Facebook mobile application’s “sync photos” function. This feature automatically uploads every photo taken on your mobile device to your Facebook account. These photos are automatically marked as private so that only the user can see them. The user would have to manually update the privacy settings on each photo later in order to make them available to friends or the public.

[Laxman] wanted to put these privacy restrictions to the test, so he started poking around the Facebook mobile application. He found that the Facebook app would make an HTTP GET request to a specific URL in order to retrieve the synced photos. This request was performed using a top-level access token. The Facebook server checked this token before sending down the private images. It sounds secure, but [Laxman] found a fatal flaw.

The Facebook server only checked the owner of the token. It did not bother to check which Facebook application was making the request. As long as the app had the “user_photos” permission, it was able to pull down the private photos. This permission is required by many applications as it allows the apps to access the user’s public photos. This vulnerability could have allowed an attacker access to the victim’s private photos by building a malicious application and then tricking victims into installing the app.

At least, that could have been the case if Facebook wasn’t so good about fixing their vulnerabilities. [Laxman] disclosed his finding to Facebook. They had patched the vulnerability less than an hour after acknowledging the disclosure. They also found this vulnerability severe enough to warrant a $10,000 bounty payout to [Laxman]. This is in addition to the $12,500 [Laxman] received last month for a different Facebook photo-related vulnerability.

Auto-sleep Hacked In PC Speakers

March 19, 2015 by Mike Szczys 29 Comments

We can commiserate with [HardwareCoder] who would rather not leave his PC speakers on all the time. The Creative T20 set that he uses turn off when you turn the volume knob all the way down until it clicks. So shutting them off means repositioning the volume each time they’re switched on again. This hack kills two birds with one stone by turning on and off automatically without touching that knob.

The system is based around an ATtiny45 and a few other simple components. It uses two ADCs to monitor the rear input channels of the PC speakers. If no sound is detected for more than one minute, the shutdown pin of the speakers’ amp chip is triggered. That’s not quite where the hack ends. We mentioned it monitors the rear input of the speakers, but it doesn’t monitor the front AUX input. An additional push button is used to disable the auto-sleep when using this front input. There is also a fancy PWM-based heartbeat on an LED when the speakers are sleeping.

[HardwareCoder] was worried that we wouldn’t be interested in this since it’s quite similar to a hack we ran a few years ago. We hope you’ll agree it’s worth another look. He also warned us that the demo video was boring. We watched it all anyway and can confirm that there’s not much action there but we embedded it below anyway.

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