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.

Curved Wood LED Lamp Needs No Fancy Tools

March 20, 2018 by Donald Papp 9 Comments

Those of us who aren’t familiar with woodworking might not expect that this curved wood and acrylic LED lamp by [Marija] isn’t the product of fancy carving, just some thoughtful design and assembly work. The base is a few inches of concrete in a plastic bowl, then sanded and given a clear coat. The wood is four layers of beech hardwood cut on an inverted jigsaw with the middle two layers having an extra recess for two LED strips. After the rough-cut layers were glued together, the imperfections were rasped and sanded out. Since the layers of wood give a consistent width to the recess for the LEDs, it was easy to cut a long strip of acrylic that would match. Saw cutting acrylic can be dicey because it can crack or melt, but a table saw with a crosscut blade did the trick. Forming the acrylic to match the curves of the wood was a matter of gentle heating and easing the softened acrylic into place bit by bit.

Giving the clear acrylic a frosted finish was done with a few coats of satin finish clear coat from a spray can, which is a technique we haven’t really seen before. Handy, because it provides a smooth and unbroken coating along the entire length of the acrylic. This worked well and is a clever idea, but [Marija] could still see the LEDs and wires inside the lamp, so she covered them with some white tape. A video of the entire process is embedded below.

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NES Controller Slider-Based Light Theremin

March 20, 2018 by Kristina Panos 1 Comment

Having never use a 555 before, [lonesoulsurfer] decided that his first foray into the world’s most popular and versatile IC would be to use a 555 to make beautiful chiptunes. For that, we commend him. He found [Dean Segovis]’ Slidersynth light-based Theremin and got to work building his own version it and stuffing it into a (knockoff!) NES controller.

For the uninitiated, a Theremin is a touch-less synthesizer that uses human capacitance and a pair of antennae to control oscillation and amplitude. In a light-based Theremin such as this one, the oscillation is controlled by the intensity of photons from a white LED and their interaction with a light-dependent resistor, also known as a photocell or ‘squiggly resistor’.

The oscillations themselves are created by wiring up the 555 as an astable oscillator, and the pitch is controlled with a potentiometer mounted on the back. It has a small built-in speaker, but [lonesoulsurfer] replaced the B button with a 3.5 mm audio jack so he can plug it into a powered speaker and really rock out. We’ve got his demo tape queued up after the break.

We love pocket instruments around here. If you prefer brass and woodwinds, this pocket woodwind MIDI controller just might draw your lips into an O.

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This Big, Bright Seven-Segment Display Is 3D-Printable

March 18, 2018 by Dan Maloney 16 Comments

Seven-segment LED displays have been around forever, it seems, and the design is pretty optimized by now. Off-the-shelf units are readily available in all sorts of sizes and colors, but if you want a really big display, you might have to roll your own. Scaling up the size doesn’t necessarily mean you have to scale up the complexity, though, if this light-pipeless jumbo seven-segment LED display is any indication.

It’s clear that [Fran Blanche] has a thing for collecting and building oddball numeric displays, like this cathode ray tube Nixie knockoff or her Apollo DSKY electroluminescent display. Her plus-size seven-segment display is far less complicated than either of those, and that’s by design; [Fran] wanted something that was 3D-printable as a single part, rather than an assembly with light pipes and diffusers. To that end, the display is just a pair of X-shaped dividers stacked on top of each other behind the display’s face. They dividers form six triangular compartments and a diamond shaped one, with each compartment opening into a segment-shaped window. One LED goes in each triangular compartment, while the double-sized diamond space gets two. That’s it — the LEDs light up the inside of each compartment to turn on the appropriate segments. Watch it in action below.

The display still needs some tweaking, but it’s big and bright and has a large acceptance angle. What’s more, it’s scalable — imagine a display the size of a sheet of plywood using LED light bulbs. We’re looking forward to [Fran]’s improvements and her next display project, which appears to use hot glue as a light pipe.

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