Author: Kristina Panos

1862 Articles

100% DIY Intervalometer Is 100% Awesome

November 16, 2014 by 14 Comments

It’s easy to tell from this process documentary that [Nagyizee] is not one to settle for prefabricated anything. He could have just bought some off-the-shelf DSLR intervalometer, but that would mean interfacing with someone else’s design through cold, soulless plastic.

[Nagyizee] wanted a one-of-a-kind tool built from the ground up. In addition to a timer, he was in the market for a light sensor and sound detection. He chose an STM32F100 ARM Cortex M3 running at 8MHz in the name of power efficiency and started designing the UI and firmware. A custom graphic library for the OLED display streamlines it even further. Once the schematic was finalized, [Nagyizee] devised a stylish and ergonomic wooden case to be milled with a tiny Proxxon F70.

With the enclosure decisions out of the way, he etched and drilled the PCB and placed the components. The light sensor needed a lens and a prism, so he made one from a 10mm LED body. Not one to miss a detail, [Nagyizee] also turned some buttons, hand painted them, and made a scroll wheel. He ends the video with a demonstration that proves it is quite capable. In addition to standard cable release mode, it handles long exposure times, sequential shooting, and capture on light, shadow, or sound. But wait, there’s more: [Nagyizee]’s creation combines modes with ease and grace.

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How To Get 50 More Zed From Your Rigol DS1054Z

November 12, 2014 by 98 Comments

[Chris] has been spending a lot of time in the wife’s sewing room lately, and things got pretty serious late last night as he hacked his shiny new Rigol DS1054Z to unlock the 1104Z capabilities lurking within.

The rumors are true, and ungoverning the software is as simple as looking up your serial number and knowing the right URL for generating a valid license. [Chris] ran into a dud site, but that’s the price of doing business in the shadowy parking garage basements of the interwebs. Once he knocked on the right door and uttered the secret word, however, he became the proud owner of 50MHz additional bandwidth, decoders for SPI, I²C, and RS-232, twice the storage depth, and all teh triggers that ship with the 1104Z.

Can’t rationalize the purchase even at the ridiculously low price point? Here’s one way to make it happen. You’ll laugh, you’ll cry, you’ll learn some French.

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Retrotechtacular: How To Teletypewriter

November 11, 2014 by 9 Comments

This week, you’re going to learn the ins and outs of the AN/GRC-46 thanks to this army training film from 1963. What is the AN/GRC-46, you ask? Why it’s a complete mobile-tactical sheltered radio-teletypewriter rig capable of CW, voice, and teletype transmission.

The film covers the components that make up the AN/GRC-46, their functions, the capabilities of the system, and proper operation procedures. There’s a lot going on in the tiny 1400lb. steel shelter, so each piece will be introduced from the ground up.

You’ll become familiar with the voltage distribution system and the AN/GRC-46’s included accessories. This introduction will be followed by a short course in RF signal transmission and the Frequency-Shift Keying (FSK) that is performed by the modulator. The ranges of both the transmitter and receiver are discussed, along with the capabilities mentioned before: CW operation using the keyer, voice operation, teletype operation, and reperforation of teletype tape.

Finally, you’ll observe a seasoned operator make contact and send a teletype message with movements so careful and deliberate that they border on mesmerizing. When he’s not sending messages or taking long walks on the beach, he can usually be found cleaning and/or lubricating the transmitter filter.

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Talking Tactile 3D Prints

November 8, 2014 by 7 Comments

Cell biology professor [Mike] has created a way for blind students to decipher microscope slides using 3D prints and the magic of capacitive sensing. His write-up focuses on a slide showing the anaphase stage of mitosis in whitefish blastula, a popular choice for studying cell division. When a student touches a certain area of the print, the capacitive sensor triggers audio playback to tell them what they’re feeling.

[Mike] started by turning a 2D image of a cell into a 3D print. To do this, he made the image black and white, and then inverted the colors so that the 3D print’s topography will correspond correctly. The talking part is handled by an Arduino Duemilanove and a Spikenzie voice shield. The latter has a somewhat limited amount of space, but is more than adequate for the audio labels [Mike] made, which are all less than three seconds long.

A hard copy of the 2D file comes in handy for making sure the cap sensors are in the right places. To make those, [Mike] cut up some floor protector pads and covered the sticky side with copper tape. These are held on the 2D image with double-sided tape. The 3D print sits on top, separated by more furniture pads at the corners. He labeled this scientific sandwich model with a 3D printed Braille label that reads ‘anaphase’. [Mike] has made the referenced STL file along with a few others available at the National Institutes of Health’s 3D print exchange site.

Triple Sensor Mailbox Alert Really Delivers

November 7, 2014 by 22 Comments

Messing with the U.S. Mail is not something we generally recommend. But if you build your own mailbox like [Bob] did, you stand a much better chance of doing what you want without throwing up any flags.

Speaking of throwing up flags, one of the coolest parts of this project is the toy mailbox inside the house that monitors the activity of the real box. When there is mail waiting, the flag on the toy mailbox goes up. Once [Bob] retrieves the mail, the flag goes back down automatically. A magnet in the real box’s flag prevents false alarms on the toy box provided the Flag Raised On Outgoing protocol is followed. Best of all, he built in some distress handling: If the mailbox door is left hanging open or the battery is low, the toy mailbox waves its flag up and down.

So, where do the three sensors come in? A magnetic reed switch on the wall of the real mailbox pairs with a magnet in the flag. To determine whether the door is open, [Bob] initially used another magnetic reed switch on the underside of the box. This didn’t work well in wet weather, so he switched to a mechanical tilt sensor. An IR LED on the ceiling and a phototransistor on the floor of the box work together to detect the presence of mail.

[Bob]’s homebrew mailbox has a false back that hides a PIC 16F1825. When the door opens, the PIC wakes up, turns on a MOSFET, and checks the battery level. It waits two minutes for the mailman to do his job and then reads the flag state. After comparing the IR LED and phototransistor’s states, it sends a message to the toy mailbox indicating the presence or absence of mail.

The toy mailbox holds a modified receiver board and a servo to control its flag. [Bob] has made the code and schematics available on his site. Walk-through video is after the jump.

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SDR: Satellite Death Receiver

November 4, 2014 by 18 Comments

Halloween may be over, but [happysat] has found a way to listen to the dead. Satellites, that is, specifically those in the 136-138 MHz and 150-400 MHz ranges. He’s using an RTL-SDR dongle and a QFH antenna to detect the death throes of decommissioned navigation and space research satellites.

[happysat] was listening to NOAA/Meteor on the 137MHz band when he made this discovery. When a satellite is near end of life, the last bit of fuel is used to push it into graveyard orbit. This doesn’t always work, however, and when the light is just right, a chemical reaction makes the long-dead batteries conduct and these satellites in purgatory transmit once more.

They’re not sending out anything proprietary useful, just unmodulated carrier that sometimes interferes with currently operational satellites on the 136-138 MHz band. [happysat] captured some audio from two of the oldest satellites that are still broadcasting, and links to a TLE set of dead satellites he created. Check out his frequency database for SDR# as well. Don’t have a weather satellite-capable antenna? Build one!

[via /r/RTLSDR]

Retrotechtacular: The Jet Story

November 4, 2014 by 31 Comments

A plane from Britain is met in the US by armed security. The cargo? An experimental engine created by Air Commodore [Frank Whittle], RAF engineer air officer. This engine will be further developed by General Electric under contract to the US government. This is not a Hollywood thriller; it is the story of the jet engine.

The idea of jet power started to get off the ground at the turn of the century. Cornell scholar [Sanford Moss]’ gas turbine thesis led him to work for GE and ultimately for the Army. Soon, aircraft were capable of dropping 2,000 lb. bombs from 15,000 feet to cries of ‘you sank my battleship!’, thus passing [Billy Mitchell]’s famous test.

The World War II-era US Air Force was extremely interested in turbo engines. Beginning in 1941, about 1,000 men were working on a project that only 1/10 were wise to. During this time, American contributions tweaked [Whittle]’s design, improving among other things the impellers and rotor balancing. This was the dawn of radical change in air power.

Six months after the crate arrived and the contracts were signed, GE let ‘er rip in the secret testing chamber. Elsewhere at the Bell Aircraft Corporation, top men had been working concurrently on the Airacomet, which was the first American jet-powered plane ever to take to the skies.

In the name of national defense, GE gave their plans to other manufacturers like Allison to encourage widespread growth. Lockheed’s F-80 Shooting Star, the first operational jet fighter, flew in June 1944 under the power of an Allison J-33 with a remarkable 4,000 pounds of thrust.

GE started a school for future jet engineers and technicians with the primary lesson being the principles of propulsion. The jet engine developed rapidly from this point on.

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