Rickroll The Masses With A Coin Cell Throwie

December 22, 2017 by Jenny List 17 Comments

If there is one educational institution that features on these pages more than any other, it may be Cornell University. Every year we receive a pile of tips showing us the engineering term projects from [Bruce Land]’s students, and among them are some amazing pieces of work. Outside the walls of those technical departments though, we suspect that cool hacks may have been thin on the ground. English Literature majors for example contain among their ranks some astoundingly clever people, but they are not known for their handiness with a soldering iron or a lathe.

We’re happy to note then that someone at Cornell who is handy with a soldering iron has been spreading the love. In the form of coin cell powered throwies that intermittently Rickroll the inhabitants of the institution’s halls of residence. We have few technical details, but they seem to be a simple affair of a small microcontroller dead-bug soldered to a coin cell and a piezoelectric speaker. If we were embarking on such a project we’d reach for an ATtiny of some description, but similar work could be done with a PIC or any number of other families.

The Cornell Daily Sun write-up is more a work of investigative journalism detailing the perplexed residents searching for the devices than it is one of technical reference. We’re pleased to note that the university authorities have a relaxed attitude to the prank, and that no action will be taken against the perpetrator should they be found.

Thus we’d like to take a moment to reach out to the Cornell prankster, and draw their attention to our Coin Cell Challenge competition. There is still time to enter, and a Rickrolling throwie would definitely qualify. This isn’t the first tiny Rickrolling prank we’ve shown you on these pages.

Thanks [Simon Yorkston] for the tip.

Coin Cells: The Mythical Milliamp-Hour

December 22, 2017 by Elliot Williams 15 Comments

Just how much metaphorical juice is in a coin cell battery? It turns out that this seemingly simple question is impossible to answer — at least without a lot of additional information. The problem is that the total usable energy in a battery depends on how you try to get that energy out, and that is especially true of coin cells.

For instance, ask any manufacturer of the common 3 V lithium 2032 batteries, and they’ll tell you that it’s got 230 mAh. That figure is essentially constant across brands and across individual cells, and if you pull a constant 0.2 mA from the battery, at room temperature and pressure, you’ll get a bit more than the expected 1,150 hours before it dips below the arbitrary voltage threshold of 2.0 V. Just as it says on the tin.

What if you want to do anything else with a coin cell? Run an LED for a decade? Pull all the energy out right now and attempt to start a car? We had these sorts of extreme antics in mind when we created the Coin Cell Challenge, but even if you just want to do something mundane like run a low-power radio sensor node for more than a day, you’re going to need to learn something about the way coin cells behave in the real world. And to do that, you’re going to need to get beyond the milliamp hour rating. Let’s see how deep this rabbit hole goes.

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Hackaday Links: December 17, 2017

December 17, 2017 by Brian Benchoff 4 Comments

Where do you go if you want crazy old electronic crap? If you’re thinking a ham swap meet is the best place, think again. [Fran] got the opportunity to clean out the storage closet for the physics department at the University of Pennsylvania. Oh, man is there some cool stuff here. This room was filled to the brim with old databooks and development boards, and a sample kit for the unobtanium Nimo tube.

The Gigatron is a Hackaday Prize entry to build a multi-Megahertz computer with a color display out of TTL logic. Now, all this work is finally paying off. [Marcel] has turned the Gigatron into a kit. Save for the memories, this computer is pretty much entirely 74-series logic implemented on a gigantic board. Someone is writing a chess program for it. It’s huge, awesome, and the kits should cost under $200.

What’s cooler than BattleBots, and also isn’t Junkyard Wars? BattleBots, but in drone form. Drone Clash was originally announced in March, but now they’re moving it up to February to coincide with the TUS Expo. What could be better than flaming piles of lithium?

The Atari Lynx went down in history as the first portable console with a color LCD. There was a problem with the Lynx; the display was absolutely terrible. [RetroManCave] found someone selling an LCD upgrade kit for the Lynx, and the results are extremely impressive. The colors aren’t washed out, and since the backlight isn’t a fluorescent light bulb (yes, really), this Lynx should get a bit more run time for each set of batteries.

Like dead tree carcasses? You need to butcher some dead tree carcasses. The best way to do this is on a proper workbench, and [Paul Sellers] is working on a video series on how to make a workbench. He’s up to episode 3, where the legs are mortised. This is all done with hand tools, and the videos are far more interesting than you would think.

If you need some very small, very blinky wearables, here’s an option. This build is literally three parts — an LED matrix, an ATtiny2313, and a coin cell battery. Seems like this could be an entry for the Coin Cell Challenge we have going on right now.

Coin Cell Powered Sea Turtle Research

December 15, 2017 by Sven Gregori 18 Comments

Hacking and tinkering are always fun and games, but one just has to appreciate when all efforts are additionally aimed towards doing something good. [Nikos] sets an example by combining his interest in technology with his passion for wildlife conservation by creating a low cost and ultra-low power temperature logger — and he is using a coin cell for it.

As the founder of a sea turtle conservation project in Greece, [Nikos] enjoys building scientific instruments that help him and his team on their mission. With a goal to log the temperature every 10 minutes over a period of at least 180 days, he designed a PCB just big enough to hold a CR2032 coin cell. Fifty of them will eventually be sealed in waterproof enclosures, and buried in the sand for the whole research duration.

Limiting the design to its bare necessities, the rest of the PCB is housing a digital temperature sensor, an SPI EEPROM to hold all the recorded sensor values over those 180 days, and an ATmega328PB clocked by a 32.768kHz crystal. Wondering what to do with all the extra, unused pins of the ATmega, [Nikos] simply routed them to be accessible through pin headers, thus turning the data logger alternatively into a coin cell powered development board.

Assuming your logging interval requirements are significantly lower, you might be thrilled to hear that [Nikos] estimates a theoretical 7+ years an average coin cell could power the data logger in sleep mode, which makes him confident to reach the 180 days goal.

This Coin Cell Can Move That Train!

December 14, 2017 by Jenny List 28 Comments

[Mike Rigsby] has moved a train with a coin cell. A CR2477 cell to be exact, which is to say one of the slightly more chunky examples, and the train in question isn’t the full size variety but a model railroad surrounding a Christmas tree, but nevertheless, the train moved.

A coin cell on its own will not move a model locomotive designed to run on twelve volts. So [Mark] used a boost converter to turn three volts into twelve. The coin cell has a high internal resistance, though, so first the coin cell was discharged into a couple of supercapacitors which would feed the boost converter. As his supercaps were charging, he meticulously logged the voltage over time, and found that the first one took 18 hours to charge while the second required 51 hours.

This is important and useful data for entrants to our Coin Cell Challenge, several of whom are also going for a supercap approach to provide a one-off power boost. We suspect though that he might have drawn a little more from the cell, had he selected a dedicated supercap charger circuit.

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The Tiniest Of 555 Pianos

December 13, 2017 by Jenny List 23 Comments

The 555 timer is one of that special club of integrated circuits that has achieved silicon immortality. Despite its advanced age and having had its functionality replicated and superceded in almost every way, it remains in production and is still extremely popular because it’s simply so useful. If you are of A Certain Age a 555 might well have been the first integrated circuit you touched, and in turn there is a very good chance that your project with it would have been a simple electric organ.

If you’d like to relive that project, perhaps [Alexander Ryzhkov] has the answer with his 555 piano. It’s an entry in our coin cell challenge, and thus uses a CMOS low voltage 555 rather than the power-hungry original, but it’s every bit the classic 555 oscillator with a switchable resistor ladder you know and love.

Physically the piano is a tiny PCB with surface-mount components and physical buttons rather than the stylus organs of yore, but as you can see in the video below the break it remains playable. We said it was tiny, but some might also use tinny.

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How Mini Can A Mini Lamp Be?

December 12, 2017 by Jenny List 4 Comments

If there is one constant in the world of making things at the bench, it is that there is never enough light. With halogen lamps, LEDs, fluorescent tubes, and more, there will still be moments when the odd tiny part slips from view in the gloom.

It’s fair to say that [OddDavis]’ articulated mini lamp will not provide all the solutions to your inadequate lighting woes, as its lighting element is a rather humble example of a white LED and not the retina-searing chip you might expect. The lamp is, after all, an entry in our coin cell challenge, so it hardly has a huge power source to depend upon.

What makes this lamp build neat is its 3D-printed articulated chassis. It won’t replace your treasured Anglepoise just yet, but it might make an acceptable alternative to that cheap IKEA desk lamp. With the coin cell LED you’d be hard pressed to use it for much more than reading even with its aluminium foil reflector, but given a more substantial lighting element it could also become a handy work light.

If 3D printed articulated lamps are your thing, take a look at this rather more sophisticated example.