Instructables user alstroemeria has lovingly documented a clock build inspired by the D/A Clock by Alvin Aronson.
Each of the paper segments is moved in or out by a servo motor to make the mechanical digital display. The whole thing is run off of an Arduino with a servo controller board and a clock module.
Over at ZeptoBars, they have an incredibly detailed “take-apart” post on what’s inside the ULN2003 seven channel Darlington driver chip. The ULN2003 is commonly used for driving LED displays—you can find it, for example, in our Mignonette game.
We often receive comments that while out microchip photos are beautiful and interesting, it is completely unclear how integrated circuit implements basic elements and form larger circuit. Of course it is impossible to do a detailed review of an 1’000’000 transistor chip, so we’ve found simpler example: ULN2003 – array of Darlington transistors.
They’ve stripped off the outer housing and put it under the microscope. They then analyzed the photos to show you what parts make up the individual transistors, resistors and diodes inside the chip.
Don McRae recently stopped by our shop last week to show off his homebrew CNC project, the “Mug Marker” — a wonderful little cardboard robot that can draw on mugs.
Much like the Mug Plotter on Instructables, it uses the same EBB controller board and stepper motors as the Eggbot, but with linear motion for the pen instead of rotation. However, unlike that version, Don has incorporated the same winch-drive mechanism that we use on the WaterColorBot to provide motion for the linear axis– meaning that it can go fast or slow, with very good accuracy.
Don laser cut the large white winch on the back of the machine from acrylic. It controls a string that pulls the pen carriage back and forth as it rides on a pair of rods:
The pen holder itself slides into some additional bearings, and has a small protrusion on the back that rests on the servo horn, allowing it to be lifted up or lowered down. Like the Eggbot’s pen-lift mechanism, this mechanism only (actively) lifts the pen, which means that it can ride over uneven surfaces, or plot on mugs with variable diameter.
Underneath the pen carriage, the opening of the mug fits onto a three-jaw coupler on the motor shaft, and the base of the mug is held against a rubber faced spring loaded plunger. Small copper tubes are used as bushings to allow the coupler pieces to rotate inward or outward to allow mugs of differing diameters to fit on. A little silicone on the surface of each of the three parts provides a gripping surface, and the upcurved lip keeps the mug from sliding too far.
Looking down through the pen carriage, you can see the mug below held in the coupler.
The chassis of the machine is made from cardboard, either hand or laser cut to slot together, and held together very cleverly with pins. The whole machine is put together from a combination of off the shelf parts and found materials, many of which are laser cut for the correct shape. For software, Don uses the Eggbot Inkscape extensions with very reproducible results.
Thanks to Don for bringing it by and letting us take pictures!
Our sincere gratitude goes out to all of our Kickstarter backers and everyone who has helped to spread the word about our WaterColorBot Kickstarter campaign. It has been incredibly rewarding to see each new pledge come in, from friends both old and new. We’re thrilled to announce that we exceeded our funding threshold of $50,000 after just over 60 hours: WaterColorBots are coming!
Today we recorded a little video that you can see on our update page of the WaterColorBot saying (well, painting) “Thank You.” One of the questions we have heard a few times (and have added to our FAQ) has been, “Can the robot go get more paint when it runs dry?” The answer is yes, as you can see in the video.
So is it all in the can and ready to ship? No, not quite yet. You may notice one goof in the video: an unnecessary color change. We’re still sanding away at the rough edges, in order to make sure that everything is ship-shape before we ship.
Thanks for all of the great questions and comments. We’ve already started adding to the FAQ based on your feedback, and we’ll continue to do so as the fantastic questions keep coming in. We’ve already got some excellent suggestions for future software directions, and changes and additions to the API. Getting real feedback from all of you about the different ways that you hope to use the WaterColorBot is immensely helpful in guiding us forward.
We’ve seen the project posted all over the internet, including on Adafruit, Boing Boing, Engadget, Tech Crunch, Gizmodo Germany, and even as far away as Indonesia at Jeruknipis. Many of you have posted it to Twitter and Facebook, and we’re grateful for all of your support.
We had planned to post an update after a couple of days, but we didn’t imagine that we would get to post about surpassing our threshold so soon! We’ll be posting more updates in the near future. There are a lot of interesting details about the WaterColorBot that we haven’t yet written about and are looking forward to sharing with you.
We’re listed as one of the sources for parts for a smart necklace project in the most recent issue of Nuts and Volts magazine. Over in our shop, you can find the resistors and switches mentioned, along with many other useful project components.
Thanks to James Sentman for the heads-up and the picture!
Today was the monthly Electronics Flea Market in Cupertino, and we came across some gems this month.
Above, an AN-OIL-IZER. The seller said her geologist father used it for testing oil purity.
It’s described in patent number 3182255, a device for capacitively testing lubricating oil (e.g., engine oil) for contaminants, by looking for changes in its dielectric constant. To use it, you place a drop of the oil in the holder, and the ball bearing into that drop of oil. The bearing is held down by a leaf spring, keeping it indexed against the holder. This forms an oil-filled capacitor between the ball bearing and a lower curved plate that is insulated from the bearing. The capacitance will vary as the dielectric constant of the oil changes due to contamination. It comes with two ball bearings, as well as oil samples for calibration.
The E-Z-Code Jr. is a tool for learning morse code: when you draw the “electric pencil” through the slots, it crosses contacts in the correct spacing to make the characters. It also has a hinged telegraph key which can be tucked away below the device.
The seller of the E-Z-Code Jr. told me that the thing I really should be photographing was this magnetron. It is a beautiful old piece of hardware, with its wave guide and high-power tube.
We found a book on Magnetic-Bubble Memory Technology. We also saw a book on tube delay memory. We’re not sure if these are a step up from the single-bit flip-flop memory in our Digi-Comp II.
I’d love to see the circuit diagram for the Cosmic Energy System by Psy Herabel [sic] Health Town, Inc.! (Sadly, their domain no longer seems to be active.)
When we recently asked the question, “Does solder expire?” you gave us some excellent answers. Many commenters had a story similar to haineux’s (sometimes replacing 1960’s with 70’s, 80’s or 90’s):
Just recently used up a spool of my father’s early-1960?s-era solder from Lafayette Radio Electronics, and now I’m working on a later-60?s spool labeled “Archer” (a Radio Shack house brand).
There might be some reason new solder is better for something, but I’ve not had any troubles doing standard PCB and parts soldering.
Steve had a great story about learning to solder with a roll of 1/8? flux core solder:
The last time it had been used (~20 years previous) it hadn’t been sealed — the flux core was open to the air. About a foot of it had dried up and evaporated. I didn’t know what I was doing so I didn’t notice at the time, but kept cursing because the solder wouldn’t stick to anything. Eventually I used the roll down to where the good solder lived and it started to flow properly, but it was a frustrating way to learn to solder. The outside of the solder was pretty corroded, a fuzzy matte gray, but it heated and flowed like anything else with fresher rosin.
To this day, whenever I solder with larger gauge solder I make sure the tip of the solder tube is closed before putting it away. I figure it will be good for another 20+ years that way.
Brad had a slightly different perspective:
Old solder might be perfectly “usable,” but try using a 10 year old spool and a brand new spool one after the other on a small-pitch SMD part, and tell me that there isn’t a big difference!
After noticing this for the first time, I never buy more solder than I can use in a couple years.
Paul reflected on different applications having different requirements:
At work we are required to throw out “expired” solder and solder paste. It is a liability problem, the FAA hates to find expired chemicals and uncalibrated equipment on their inspections.
At home I have used twenty year old rolls. My stuff at home is just for my use and no ones life is at risk.
So the general consensus seems to be that rosin core solder will work nearly indefinitely so long as the rosin isn’t affected by storage conditions. Even then, as long as the bad section is removed, the rest will work fine. A few connoisseurs prefer newer solder (especially for small parts), and industrial applications may require strict adherence to expiration dates, but many of the rest of us will continue to use our (long) expired solder until it’s gone.
Over the course of the past few years, we’ve been writing occasional “Basics” articles, about introductory topics in electronics and microcontrollers. In the spirit of making things easy to find, we’ve now tagged them so that you can find them with this link, and we’re collecting them together in this index that will be updated from time to time.
Our “Basics” articles about electronics in general:
Additional “Basics” articles about working with AVR microcontrollers:
Just in time for the Fourth of July, Jeremiah Warren created an incredible relatively low-budget “bullet time” rig— with a 240 fps GoPro camera mounted to a ceiling fan —to photograph fireworks. He posted a full writeup showing how to build it on his web site.
The clever hack about using the GoPro on the ceiling fan is thanks to Mark Rober, who showed how to do it back in May, mostly with smaller-scale subjects. But Jeremiah has taken the idea and run with it, adapting it for larger-scale photography.
And as you can see, the results are simply fantastic.You can find more videos and the full how-to on Jeremiah’s site.
Super Awesome Sylvia and I were invited to attend Bring Your Kids to Work Day at Atmel recently. (Atmel, of course, is the company that makes the microcontrollers found inside Arduino products and in many of our own projects and kits.) We were there to help provide tangible, interesting, and playful examples of how Atmel chips can be used. And of course, we weren’t going to miss an opportunity to visit Atmel headquarters!
The biggest hit with the kids were the Octolively interactive LED modules (sporting the Atmel ATmega164P). When the kids waved their hands over them, the LEDs would light up and ripple. Some of the kids would start out by poking and grabbing at the LEDs until they lit up, but as soon as I told them it would work “even without touching it” their eyes would get big, and they’d wave their hands over the top, enthralled.
Some of the other things we brought were our handheld game, the Meggy Jr RGB (with the ATmega328P); a Bulbdial Clock (Atmega328P again), which points rings of LEDs at different heights down at a central point to create shadow hands of different lengths; our giant Alpha Clock Five (ATMega644A); and the Larson Scanner (ATtiny2313A), which lights up nine red LEDs to make a scanning robot eye.
Another project that captured the kids’ attention was a Keepon by BeatBots. Other demonstrations included a quadcopter and a hacked hexabot.
We got to have lunch in the bright sun in the courtyard with Avary Kent, who was demonstrating the PuzzleBox, a brain-controlled helicopter.
Sylvia got to give the PuzzleBox a try, triggering it to fly as soon as she concentrated hard enough.
After lunch, we got to tour of a couple of labs. This workbench was well stocked with a Metcal soldering iron (our favorite) and lots of tools and supplies.
Apparently the poor Pleo on this bench needed some repair.
This machine is for inspecting and testing chips after they have been removed from their housing.
We got to go into the RF anechoic chamber, and watch as our cell phones stopped receiving any signals.
We also had some time to hang out and horse around with friends new and old. Our friend Paul Rako seemed to be having as much fun as the kids.
Thanks to Paul and Atmel for inviting us to visit!
