LED Water Wheel Display Is Dekatron-tastic!

led-ring-final

Sometimes, it’s the simple things that mesmerize. [JohnS_AZ] has created a simple dekatron style LED ring, but we can’t seem to stop watching his video. [John's] LED ring began as a visual indicator for his Hackaday Prize entry, a water consumption display. Judging by his website, [John] is a bit of a display nut. Nixie tubes and huge clocks feature prominently.

We’ve seen plenty of LED projects using the trusty 74xx595 8-bit shift register. [John] personally isn’t a fan, as the entire chip is only rated to drive about 50mA. While hackers routinely push the chip several times past this limit, [John] found a chip designed for the task in the Texas Instruments TLC59282 16 channel constant current LED driver. (PDF link) While more expensive than the ‘595, the 59282 makes life much easier. Only one resistor is needed at the chip’s current sense pin, rather than a current-limiting resistor for each LED. The 59282 also provides a blank input, which is perfect for driving with PWM.

[John] designed a simple PCB with a the 59282 driving a ring of 16 LEDs. While he waited for the boards to come in, he wrote some test code for a Microchip PIC16F1509. [John's] code is not optimized, but that makes it easy to see exactly which bit patterns he’s writing to the LEDs. It all makes for a great demo, and reminds us of those old Dekatron tubes.
It’s the demo video that makes this project. Click past the break and give it a watch. After several long days of judging entries, a really nice LED ring might be just what the doctor ordered.

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Cold War Clock is all Tubes

A clock built from tubes

 

Clocks are great projects to build. They serve a real purpose, and there’s a wide variety of ways to implement a unique timepiece. [Hank]‘s Cold War Clock only uses parts and technologies that were available in 1959. It contains no semiconductors, but has an audible alarm and reasonable time accuracy.

Looking through the hand drafted schematics, you’ll find a number of Dekatron tubes. These vintage components are used as registers to store and count the time. [Hank] found some cheap Soviet Dekatrons, but had to machine his own sockets to connect them. These tubes do the counting, but the actual display consists of nixies.

A cost estimate puts this clock at $2130 in 1959, which equates to $17040 today. Clearly this would be outside the price range of most hobbyists. The actual build cost [Hank] around $1600.

There’s some intricate details in this build. The front panel has an authentic look to it, and the manual has instructions for “demolition of clock to prevent enemy use.” [Hank] calls it a “creative anachronism.” In a sense, it’s a reproduction of a product that never actually existed.

A video of this clock in action, including the Cold War era alarm, is after the break.

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Drive bay form factor dual Dekatron readouts for RAM and CPU usage

optical-drive-dual-dekatron

The two circular displays seen above are Dekatrons built into an optical drive enclosure. [Matt Sylvester] picked up a couple of different types of these tubes on eBay. He etched his own driver, and was able to control them with an Arduino. After a few months went by he decided to revisit the project to see if it would work as a CPU and RAM usage meter.

These tubes need high voltage to get the neon display glowing brightly. This raised some concerns about having those voltage levels inside of his PC, as well as the noise which may be introduced by the supply. To deal with those issues [Matt] gutted an old optical drive, using its case to physically isolate the circuitry, and some optoisolators to protect the logic connections. His driver board uses an ATmega328 running the Arduino bootloader. It connects to the PC using an FTDI USB to Serial cable. This makes it a snap to push the performance data to the display. It also has the side benefit of allowing  him to reprogram the chip without opening the case.

If you can’t find one of these tubes for your own project consider faking it.

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Halloween Props: Pie of Sauron

pie-of-sauron

[Richard] combined creative carving with vacuum tube electronics for a unique pumpkin offering. He used the stencil-and-cut method of carving, making use of an inexpensive carving kit for great results. He salvaged an LED module from a flashlight to provide the internal illumination, but it’s the center feature that we like the best. [Richard's] used a glow-transfer counting tube, or dekatron, which provides something like a circular cylon eye to the project. There’s a video of this after the break.

You might not have access to a wicked-looking dekatron but we’re guessing you’ve got a microcontroller and some LEDs lying around that can serve as a stand-in for one night. We’d love to do a reader jack-o-lantern roundup, so if you build something, send us a picture!

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Dekatron kitchen timer

tube

[Eschlaep] put together this beautiful kitchen timer using a dekatron. We see all kinds of tube projects, but dekatron projects are fairly rare. The over all aesthetic is quite nice, though we’d be tempted to find a way to protect that high voltage circuit.

[via the Hack a Day flickr pool]

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