Precision Voltage Reference Source

[barbouri] found a few old (vintage?) parts from the early ’80’s while rummaging through his parts bin, and quickly spun out a small PCB to build a 10.000 V reference using these old ICs. Throwing together a small number of parts, he was able to build a source which might be good enough to use as a reference for another circuit or provide a quick calibration check for some of his bench instruments that have a resolution of 1 mV or maybe even 100 μV.

The AD584* pin programmable precision voltage references have been available since the ’80’s and offer four programmable output voltages of 10.000 V, 7.500 V, 5.000 V, and 2.500 V. The chip is laser-trimmed to ensure high accuracy and low temperature coefficient and requires just a few external components to function. It is available in TO-99 hermetically sealed metal can and 8-pin DIP variants. The “S” version of the device that [barbouri] used provides a temperature coefficient of 30 ppm/°C max over a -55 °C to +125 °C temperature range but other versions of the chip offer a better stability. Analog Devices seem to have discontinued the “L” version (pdf), since it is no longer listed in the current data sheet, but you can still get them from a few sources. The “L” version has a temperature coefficient of just 5 ppm/°C.

Using quality parts such as high stability resistors and TO-99 PTFE socket with gold-plated contacts, his observations confirm that the unit is stable within 30 μV, with a very slow voltage increase of a few microvolts every 6 hours. A 15 V linear regulator powers the device with input power coming from an external wall wart. A small aluminum enclosure houses the device, with two gold-plated 4 mm sockets for the output. If you would like to build your own, his board design is hosted on OSH park, or you can download the Eagle CAD design files. He’s posted all links on his blog post, and provides part numbers for all of the parts used. [barbouri] has been doing a good job of building handy devices for his work bench – check out his well-built milli Ohm Meter that we had featured earlier.

Bringing MATLAB to a Vacuum Near You

The essence of hacking is modifying something to do a different function. Many of us learned as kids, though, that turning the family TV into an oscilloscope often got you into trouble.

These days, TVs are flat and don’t have high voltage inside, but there’s always the family robot, often known as a Roomba. Besides providing feline transportation, these little pancake-shaped robots also clean floors.

If you don’t want to evict the cat and still get a robust domestic robot platform for experimentation, about $200 will get you a Roomba made to be hacked — the iRobot Create 2. [Gstatum] has a tutorial for using a Raspberry Pi and MATLAB to get one quickly running and even doing basic object recognition using the Pi’s camera.

The code even interfaces with Twitter. The impressive part is the code fits on about a page. This isn’t, however, completely autonomous. It uses a connected phone’s sensor’s so that the phone’s orientation controls the robot’s motion, but the robot does use sensors to prevent driving into walls or falling off a cliff. It also can detect being picked up and uses the Pi’s camera to detect a green flag.

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Dumb Box? Make it Really Smart!

[Stephen Harrison]’s Really Smart Box is a great concept, it’s simultaneously a simple idea while at the same time being super clever. The Really Smart Box isn’t really a box; it’s a drop-in platform that can be made any size, intended to turn any dumb storage box into one that helps manage and track levels and usage of any sort of stock or consumable.

It does this by measuring the weight of the stuff piled on top of it, while also monitoring temperature and humidity. The platform communicates this information wirelessly to a back end, allowing decisions to be made about stock levels, usage, and monitoring of storage conditions. It’s clearly best applied to consumables or other stock that comes and goes. The Really Smart Box platform is battery-powered, but spends most of its time asleep to maximize battery life. The prototype uses the SigFox IoT framework for the wireless data, which we have seen before in a wireless swimming pool monitor.

This is still just a prototype and there are bugs to iron out, but it works and [Stephen] intends to set-and-forget the prototype into the Cambridge Makespace with the task of storing and monitoring 3D printer filament. A brief demo video is embedded below.

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Swarm of Servos Plays this Robotic Glockenspiel

It’s the happiest sounding instrument in the marching band, and it’s got the best name to boot. It’s the glockenspiel, and if this robotic glockenspiel has anything to say about it, the days of human glockenspielists are numbered.

In its present prototype form, [Averton Engineering]’s “Spielatron” looks a little like something from a carousel calliope or an animatronic pizza restaurant band. Using a cast-off glockenspiel from a school music room as a base, the Spielatron uses four mallets to play all the notes. Each key is struck by a mallet secured to a base made of two servos. For lack of more descriptive mallet terminology, these servos provide pan and tilt so the mallet can strike the proper keys. The video below shows the Spielatron’s first recital.

An Arduino runs the servos and a MIDI interface; unfortunately, this version can’t play chords and is a little limited on note length, but upgrades are on the way. We’ve seen a robotic glockenspiel before with a similar design that might have some ideas for increasing performance. But if you’re looking for a more sublime sound, check out this dry ice-powered wind chime.

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Glue Gun Teardown Reveals Microcontroller Mystery

[electrobob] got a Bosch GluePen cordless hot glue gun. The thing has some nice features — it heats up in fifteen seconds, and charges via USB, and is generally handy for those small and quick jobs that hot glue guns were made to perform. At first glance it seems like a huge improvement over the plug-in varieties, which seem to take forever to heat up when all you need is a quick dab of glue.

As cool as the product sounded, [bob] did what any right-minded hacker would do and opened it up to see how that sucker work and found an ATtiny24A inside. What’s most interesting is that there appears to be no temperature regulation or sensing capability, with the exception of the thermistor in the battery-charging circuit. It’s an intriguing mystery.

The ATtiny controls a power MOSFET that brings the heating element to “approximately 170 degrees” according to the manual. [bob] could find no temperature regulation of the hot end, which measures a steady 12 V at the gate of the transistor then entire time the glue gun is powered on.

That ATtiny24A that runs the whole thing packs 12 GPIO pins, 4 PWM channels, and 2 KB program memory. It appears a bit overpowered for a glue gun controller. [bob] found one of the Tiny’s pins connected the heating element and another to the charging circuit. Maybe a shutoff in case the battery catches fire?

Without a clear shot of the back of the board, it’s a bit of a guessing game, but eight of the twelve GPIO pins appear to be in use. Leave your theories in comments. And if you’ve got any bright ideas about what to do with the remaining four GPIO pins, have at it!

For another of [bob]’s tool hacks, check out his constant current sink we posted earlier this year.

Hackaday Store Discounts to Satiate the Shopping Urge

Score everything in the Hackaday store for 50% off right now.

Today is Thanksgiving in the United States, a time when people migrate back home to spend time with families, fill themselves with Turkey and cranberry sauce, and are inevitably dragged out to the big box stores in search for that one great deal to satisfy their consumer urge.

Whether you observe the holiday or not, you can grab some geeky stuff from the Hackaday Store without the early rise or the need to be in a specific place. You’ll find a collection of some of our favorite hardware, sweet Hackaday apparel, and our beloved print goods sprinkled in. Give it a look.

Facedancer21

Fly a quad indoors with the CrazyFlie 2.0, impersonate USB devices with the Facedancer21, and have a blast with our favorite clock kit, the Bulbdial Clock.

MeARM Pocket Sized Robot ArmGoodfet ProgrammerUSB Tester Bundle

Assemble and program your own robotic MeARM, be the master of all things serial bus with the GoodFET42, and monitor the juice flowing to your USB device with the USB Tester 2.0.

Hundreds of Tindie Items are also on sale this weekend. Tindie where you go to find unique and cutting edge hardware sold by those that designed it. Check out to the Tindie sale page for a complete listing of items going on sale now and throughout the weekend.

Building a Skyrim Quest Marker

I’m working on a Skyrim quest marker. You probably know what this is even if you never have played the game. When a character or location in the game relates to a quest, an arrow floats over it so you don’t miss it. If it’s a book, the book has the arrow floating over it. If it’s a person, it floats over that character’s head. It is that quest marker I aim to re-create.

I sat down in front of my sketchbook and drew the basic parameters. I wanted it to be approximately to scale to the human/elf/orc heads it usually floats above. I ended up going with around 9 inches from top to bottom. In terms of thickness, any amount of blatant dimensionality is bad, as the game element exists in only 2 dimensions. That said, I will be re-creating this thing in the real world, and LEDs and acrylic and plywood and other things need to go inside.

I decided to make it around 1.25 inches thick, which would include enough space for a 9V battery if I so chose, plus a proto board and microcontroller.

Designing the Electronics

Before I finalized the dimensions I had to design the circuit. Originally I looked at Adafruit’s backlight LED panels, but I felt it would be too hard to fit into the pointy parts of the enclosure, both physically and in terms of light distribution. Instead I went with a strand of cold white LEDs, not individually addressable but only require power and GND to light up. However, the strand is WAY too bright straight from the battery. Fortunately, the strand is PWMable so I am using an Adafruit Trinket ATtiny85 breakout to dim it down somewhat.

I chose a TIP-120 for the switching, a part highly recommended by our own [Adam Fabio]. Power supply will be my wall wart; if I were to take it out into the wild, I could put a 9V battery inside the enclosure — there’s room — but I think I’ll just have it at home this time around.

Designing the Enclosure

I decided to be flexible with my design. I was going use the laser cutter to cut each layer of the marker out of eighth-inch material. The front will have a bezel holding the acrylic in place, while the back is just a blank piece of plywood. The interior layers, of unknown quantity (as I designed it) would determine the overall thickness of the marker.

I opened up Inkscape and went to work designing the layers. I did everything in a single Inkscape file with each layer corresponding with a similar layer on the design.

Closer to lasering, when I have a good sense of the projects’s final parameters, I’ll distribute the layers on a series of 12”x12” Inkscape canvases, and I’ll print directly from these. This will allow me to cut some filler projects in the unused portion of the boards, because I’m cheap like that.

The topmost bezel was easy — it’s supposed to look a specific way. I dropped a GIF from the ‘nets into Inkscape and traced it. I duplicated that layer and made the bottom plate, which is basically just a filled-in version of the bezel. There needed to be the vinyl for the light-emitting part, with some sort of bezel keeping it in place. There also needed to be a board for the LEDs, and beneath the LED board there needed to be room for a small circuit board.

I ended up making the whole thing 10 layers thick: Beginning from the top: the outer bezel; then the acrylic and its carrier, which nestle together — I didn’t want any light escaping from the sides. The third layer is an “under bezel” which lifts the acrylic up 1/8” because the LED strips are covered in a little “hill” of plastic. Fourth, the LED plate, painted white with lengths of LED strip attached to it.

I consider those four layers to be the top of the project. The next six are the bottom, consisting of five identical layers making up the electronics compartment, with the back plate, which also has a hole for the power supply and also mounts the protoboard. Each layer is 1/8″ thick, for an overall thickness of 1.25″ — not too bad. It’s somewhat on the heavy side. (By the way, you can find the Inkscape file in the project page.)

Lasering

The first fifteen minutes of lasering was hell, as I got all the settings figured out. But once I got everything dialed in, it was a breeze.

The layers were split onto 12″x12″ sheets, with two layers per. So I imported 1″x2″ rectangles with horse shapes on them, and you can see them on the right. We use these in my gaming group for horses, with a figure sitting on top of it to show he or she is mounted.

Once I got dialed into my favorite settings, the lasering went quite well. The wood was about one notch lower in terms of quality than what I’m used to, and I felt like the glue was just a little more refractory or whatever. Still, most of the parts came out perfectly.

I was mostly worried about the acrylic. I took a chance with some translucent white acrylic I found on Amazon. Having never used it before, or had a clear understanding (sorry) of how translucent it was, I bought it sight unseen. Furthermore, I had enough real estate on my 12″x12″ sheet for maybe 3 cuts, so I wanted to get the right settings ASAP.

It worked better than I could have hoped. Someone at the hackerspace had written the best ratio of speed and power on the laser cutter room’s whiteboard walls — 15 speed, 8 power. I ran it through twice to be sure, but it came out perfect, and slid into place like a charm.

The Build

I glued the bottom six layers right there in the hackerspace, as well as the two-layer carrier for the acrylic. All I needed to do was paint the thing, add the electronics, and bolt it together.

Originally I’d envisioned a battery pack inside a harness of some sort, with a black-painted PVC pipe hoisting the marker overhead. That seems like a lot to tackle between now during my first run at the project, so I converted the idea to a tabletop version that uses a wall wart.

When I was prototyping the electronics it had occurred to me that I might be a little ridiculous about the Trinket — what if it didn’t need to be PWMed down? Oh, but it does. LED strips run at full brightness are awfully bright, and that cold white that has all the subtlety of a klieg light. They definitely need to be PWMed down.

The strip comes with a 3M adhesive backing, which was great, However, the solder pads that were most accessible were on the underside, as the top is covered in a plastic bubble that is hard to cut away, even with a sharp knife.

For  the future development, I plan to swap in an ESP and use it as a Twitter alert. In addition, the enclosure was hastily designed and lacked a certain polish. For instance, I would like to use trapped nuts on the top three layers to secure the front bezel from behind, so it doesn’t have those intrusive socket heads showing — or at least inset them somehow.

But all in all I’m happy to have the enclosure work out so well the first try. After countless lasered projects with every grade of success from “abject debacle” on up, maybe I’m starting to get a hang of it! Check out the project page on Hackaday.io.