Years ago, if you wanted to track employee hours, you needed to have them punch a time card. Saunders Machine Works, however, uses a facial recognition system running on an iPad for this purpose, meaning they had to figure out how to sense employees of different heights. What they came up with is a fixture that automatically raises and lowers the tablet, using a stepper motor and linear rails.
The project employs a Lidar sensor on the bottom of the device to detect employee presence, and another above the iPad’s mounting hardware to sense when it’s at the correct height, moving until the top sensor is clear. Control is provided by a pair of Arduino Nanos.
While many enjoy roller coasters, few can claim the same dedication of engineer Matt Schmotzer, who 3D-printed a 1/25th scale replica of Invertigo, a boomerang coaster at Kings Island in Ohio.
As reported on 3D Printer Chat, the CAD model took only a week to complete, but 3D printing this 4’ x 8’ creation took an incredible 450 hours. This doesn’t include the countless hours spent assembling and debugging it.
The coaster runs on an Arduino Mega, using 42 of the 54 available IO pins. This allows it to not only lift and drop the coaster, but also feature details like actuated gates and restraints to keep the tiny imaginary passengers safe.
Do you and your friends have a favorite cocktail? If so—and if it has three ingredients—then this Arduino-based cocktail machine from YouTuber “GreatScott!” may be worth checking out.
The device is capable of mixing three liquids, which in GreatScott’s case consist of vodka, cranberry juice, and grapefruit juice (also known as a Sea Breeze), in a drink size selected via a rotary encoder and LCD screen.
An Arduino Nano provides the brains for this operation, and each component is poured using a series of three peristaltic pumps. Meanwhile, a load cell underneath the glass holder ensures that the correct amount of liquid is dispensed.
The same setup could be used to make different three-ingredient drinks with a little programming work, or it could be expanded into a multi-drink unit with the addition of a few more pumps. You can see it in action below!
If you are really enjoying a song, you may start to bob your head to the tunes, but what if you could instead create actual music with this subtle movement? That’s exactly what Andrew Lee’s “Nod Bang” system accomplishes.
An accelerometer mounted to a pair of headphones senses nods in order to dictate the beat, while four 3D-printed arcade buttons are used to select which sounds will be played. An Arduino takes these inputs and passes them to a computer via a MIDI USB interface. The board also controls lights on the buttons for visual feedback.
While working on a project recently, I required a capacitor of around 1000 μF and went rummaging through my collection of parts. No luck there. At that point I’d usually go through my collection of junk electronics and computer motherboards, but I had recently gone through and tossed the stuff that had been laying around for as long as I could remember. No matter, I thought. I’ll just head over to RadioShack and…
Now, I have been accused of many things over the years, but “deep” is certainly not one of them. Yet, at this moment I had what could only be described as an existential crisis. There is no RadioShack, not in my state at least. I don’t live in an area that’s blessed with a maker “scene”, so no independent shop or even a hackerspace within reasonable driving distance of me either. I could order it online of course, but everyone’s trying to sell them in bulk and shipping will take a few days at least. A few days? Who knows where my interests will be in a few days. How can I get anything done under these conditions?
Desperate times call for desperate measures, so I got in the car and took a ride to the only place I knew where I could by electronic components for cheap: Goodwill.
Second Hand Salvage
If you aren’t familiar with Goodwill, it’s a second hand store where all manner of goods are sold, usually for a pittance. While the stock at Goodwill tends to be largely clothes, each one of their locations I’ve ever been into has had an electronics section in a back corner somewhere that has piles of crusty old VCRs, tape decks, tube televisions, etc. Basically any antiquated piece of consumer electronics that the owner felt too bad to just throw in the garbage: you’ll find it here. Of course, Goodwill is not really unique in this regard. If you’ve got a local second hand or thrift store, it’s likely they have a similar area.
In a RadioShack-less world, I suggest you become well acquainted with these types of stores and the wares they tend to deal in. It might be time to start checking in every week or so if it’s not out of your way. Because if you aren’t lucky enough to live in a hotspot of makers or hackers, and are too proud to garbage pick, stores like this may as well be your RadioShack now.
During my trip, I had no problem finding what I was looking for. There were plenty of VCRs and radios lying around, none more than $5 each. If you’re looking for good sources of through-hole components, you’ll probably want to stick to the older and cheaper looking hardware. The higher end devices would be more likely to have switched over to SMD components or other miniaturization techniques which might make salvaging parts from them more annoying.
In my case, I was lucky. The VCR that I selected came apart easily, and had its power supply on a nicely removable module that I was able to yank right out of the case. Inside it looked a bit nasty, some kind of sticky yellow fuzz covered most of the internals of the machine; if I had to guess, I would say this came from a smoker’s home. But for a $3, we can’t be too picky.
Power supplies are always a wealth of electrolytic capacitors, and it only took a few seconds to identify a 1000 μF capacitor that didn’t appear to be bulged. Remember that the hardware you’re dealing with can be rather suspect, and a close visual inspection is in order for all parts you are considering putting into your project.
After getting it freed from the PCB, I was able to check it with my multimeter and see it was at about 900 μF, which puts it within the tolerances for this kind of capacitor. Electrolytic capacitors are notorious for failing with age, and care should be taken to make sure you aren’t going through all this trouble for nothing.
The Day is Saved, For Now
In the end, I was able to get the capacitor I was after (plus a load of other passives and components I pulled out of the VCR) in about an hour and for only a few dollars. Certainly a better deal than ordering a single capacitor online, but still something I’d have rather avoided. Now that there are no more local electronic component shops in my area, it may be time to bite the bullet and just load up on bulk passives from eBay before I actually need them. But having a contingency plan like this never hurts.
In this dystopian post-RadioShack wasteland, where are readers getting their components? Are you lucky enough to live in an area where parts can be locally sourced? Are you buying in bulk online and just hoping you can predict what parts you’ll need? Maybe you’ve gone full Mad Max and how just build everything out of what can be found in the trash?
Santa’s Shop is an amazing Christmas display consisting of trains, animated figurines, a rotating tree, and several other interesting holiday-themed gadgets.
The decoration features hundreds of 3D-printed parts and many handmade characters, controlled by 46 servos and a total of 12 Arduino boards. Bringing the installation to life was no small task, requiring over 2,000 hours of labor for creators Mike and Annelle Rigsby.
More details on the project can be found in this write-up. You can also see it in action in the video below, or on display live in the window of the Brightway Insurance Agency in Gainesville, Florida this month.