Color Spaces: The Model At The End Of The Rainbow

March 30, 2018 by Kerry Scharfglass 23 Comments

When I learned about colors in grade school everything started with red, yellow, and blue and getting fancier colors was easy. I mixed some blue into my yellow to get green, or into red to get purple, and so on. After painting enough terrifying “art” for my parents, this made intuitive sense. That is until my mind was blown by the revelation that this wasn’t always true!

To make the same colors with light instead of paint I had to use red, green, and blue, not yellow. It was until much later when trying harness banks of RGB LEDs that this knowledge became useful. I was struggling to make my rogue diodes look quite the way I wanted when I stumbled into the realization that maybe there was another approach. What did the numbers representing R G and B actually mean? Why those parameters? Could there be others? [Elliot Williams] has written about the importance of gamma correction and adjustment for human perception of color, but we can ask a more fundamental question. Why do we represent color this way at all?

Continue reading “Color Spaces: The Model At The End Of The Rainbow” →

An LED Effect For Every Occasion

March 28, 2018 by Kerry Scharfglass 13 Comments

Quality software development examples can be hard to come by. Sure, it’s easy to pop over to Google and find a <code> block with all the right keywords, but having everything correctly explained can be hit or miss. And the more niche the subject, the thinner the forum posts get. Bucking the downward trend [HansLuijten] provides an astoundingly thorough set of LED strip patterns in his comprehensive post titled Arduino LED strip effects.

Don’t let the unassuming title lead you astray from the content, because what’s on offer goes beyond your average beginner tutorial on how to setup a strand of NeoPixels. [HansLuijten] is thorough to a fault; providing examples for everything from simple single color fades and classic Cylon eyes to effects that look like meteors falling from the sky. Seriously! Check out the videos on their webpage. Those chasing lights you see around theater signs? Check. Color twinkle and sparkle? Check. Color wipes and rainbow fades? Check, and check. Continue reading “An LED Effect For Every Occasion” →

It’s A Nixie! It’s A VFD! No, It’s A Custom LED Display In A Tube

March 26, 2018 by Dan Maloney 42 Comments

Like the look of Nixies but they just seem a little overdone? Or perhaps you just don’t want the hassles of a high-voltage power supply? Then maybe these faux-Nixie LED “tube” displays will find a way into your next clock build.

For his 2018 Hackaday Prize entry, [bobricius] decided that what the world needs is a Nixie that’s not a Nixie. To that end, each display is formed by seven surface-mount LEDs soldered to a seven-segment shaped PCB and slipped into a glass tube. The LEDs are in 4014 packages so they’re only 4 millimeters long, but what they lack in size they make up for in brightness. We’re not sure if it’s a trick of the camera, but the LEDs certainly seem to put off a bluish glow that’s reminiscent of vacuum-fluorescent displays — it’s like a Nixie and a VFD all rolled up in one package. The current case, which hides the clock circuitry on the lower part of the PCB, is just plastic, but this would look spiffy in a fine wooden case.

Could this be another Nixie tube killer that never was? Perhaps, but wherever it ends up, we like the look of it, and we’re glad it’s one of the early Hackaday Prize entries. Have you got something to enter in the greatest hardware competition on Earth? If not, get cracking!

Great Emergency Lights From Not-So-Great UPS

March 24, 2018 by Jenny List 25 Comments

We know your shame. Like you, we wanted to save some scratch and bought the bottom-of-the-range UPS, only to discover that it is no use to man or beast as it lacks the power to perform any reasonable task. It’s now sitting in a corner, to gather dust as its batteries deteriorate.

Not so fast with the UPS abandonment! [rue_mohr] came up with a modification for a small APC UPS that turned it into something a little more useful. Removing the mains inverter from the picture with a few displaced wires and PCB mod, the UPS is now a 12V battery with a mains charger and power outage detection built-in. In this state it’s the perfect power pack for some 12V LED strips used for emergency lighting. There is a handy 3D print that fits the rear socket cut-outs on the US version of the device and provides apertures for a pair of DC power jacks.

This is a relatively simple hack, but we like it for taking the focus away from the obvious part of the UPS, its mains inverter, and turning to the batteries as the main event. It’s a relatively tiny device, but in the past we’ve featured a UPS at the other end of the scale being used for power back-up to a whole house. Meanwhile we’d like to take a leaf from the [BOFH]’s book, and recommend that the most important piece of infrastructure requiring a UPS is the sysadmin’s coffee machine.

Let There Be Light Rings!

March 24, 2018 by James Hobson 11 Comments

[Brandon Rice] is at it again — this time to level-up your photography and video production skills with a diffused light ring.

Inspired into creating more video content, he wanted to forgo the price tag associated with consumer lighting rigs. A 19″ diameter ring fit his requirements, but since the only laser cutter he had access to was limited to 12″x14″, he was forced to assemble it in pieces. As he screwed it together, he hid the M6 screws by pointing them ‘forwards,’ to be hidden underneath the diffusing vellum material. Liberal application of hot glue has kept the arched vellum and the LED strips in place with only a nominal number of burned fingers.

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Stecchino Game Is All About Balancing A Big Toothpick

March 23, 2018 by Donald Papp 5 Comments

Self-described “Inventor Dad” [pepelepoisson]’s project is called Stecchino (English translation link here) and it’s an Arduino-based physical balancing game that aims to be intuitive to use and play for all ages. Using the Stecchino (‘toothpick’ in Italian) consists of balancing the device on your hand and trying to keep it upright for as long as possible. The LED strip fills up as time passes, and it keeps records of high scores. It was specifically designed to be instantly understood and simple to use by people of all ages, and we think it has succeeded in this brilliantly.

To sense orientation and movement, Stecchino uses an MPU-6050 gyro and accelerometer board. An RGB LED strip gives feedback, and it includes a small li-po cell and charger board for easy recharging via USB. The enclosure is made from a few layers of laser-cut and laser-engraved material that also holds the components in place. The ~~WS2828B~~ WS2812B LED strip used is technically a 5 V unit, but [pepelepoisson] found that feeding them direct from the 3.7 V cell works just fine; it’s not until the cell drops to about three volts that things start to glitch out. All source code and design files are on GitHub.

Games are great, and the wonderful options available to people today allow for all kinds of interesting experimentation like a blind version of tag, or putting new twists on old classics like testing speed instead of strength.

LED Strips Are So Hot Right Now

March 23, 2018 by Jenny List 111 Comments

Sometimes there will appear a figure that flies in the face of reason, and challenges everything you think you know about a subject. Just such a moment came from [Chris Taylor] at Milton Keynes Makerspace when he characterised a set of LED strips, and the figure in question was that he found an LED strip creates the same amount of heat as its equivalent incandescent bulb.

We can hear your coffee hitting the monitor and your reaching for the keyboard to place a suitably pithy comment, because yes, that’s a pretty unbelievable statement. But it’s no less true, albeit that the key to it lies in its details. If you have a 100 W incandescent bulb, 88% of the energy is radiated as light and infra-red, leaving 12 W heating the bulb itself. To get the same light output from an LED meanwhile we’d only need 17 W, of which 11.9 W would be left to heat the LED. Which means that an LED strip can get as hot as an incandescent bulb with equivalent light output, and he’s run some tests to prove it.

If you’ve worked with LEDs, you’ll know that they get hot. But to learn that they have the potential to get as hot as their incandescent equivalents is something of a eye-opener, and should demonstrate the need for adequate thermal mitigation. It’s easy to take them for granted, and we’ve taken a look before at some of their safety pitfalls.

Disclosure: [Jenny List] is a member of MK Makerspace.