Li-Ion Tech Staring Into The Abyss With Note 7 Failure

Unless you’ve been living under a high voltage transformer, you’ve heard about the potential for Samsung’s latest phone, the Note7, to turn into a little pocket grenade without warning. With over 2.5 million devices in existence, it’s creating quite a headache for the company and its consumers.

They quickly tied the problem to faulty Li-ion batteries and started replacing them, while issuing a firmware update to stop charging at 60 percent capacity. But after 5 of the replacement phones caught fire, Samsung killed the Note7 completely. There is now a Total Recall on all Note7 phones and they are no longer for sale.  If you have one, you are to turn it off immediately. And don’t even think about strapping it into a VR headset — Oculus no longer supports it. If needed, Samsung will even send you a fireproof box and safety gloves to return it.

Every airline has been broadcasting warnings not to power on or charge a Note 7 on a plane. Image Source: CNET

It should be noted that the problem only affects 0.01% of the phones out there, so they’re not exactly going to set the world on fire. However, it has generated yet another discussion about the safety of Li-ion battery technology.

It was just a few months ago we all heard about those hoverboards that would catch fire. Those questionably-engineered (and poorly-named) toys used Li-ion batteries as well, and they were the source of the fire problem. In the wake of this you would think all companies manufacturing products with Li-ion batteries in them would be extra careful. And Samsung is no upstart in the electronics industry — this should be a solved problem for them.

Why has this happened? What is the deal with Li-ion batteries? Join me after the break to answer these questions.

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Maslow Brings The Wall Plotter Into The Woodshop

Hanging plotters, or two steppers controlling a dangling Sharpie marker on an XY plane, are nothing new to our community. But have you ever thought of trading out the Sharpie for a wood router bit and cutting through reasonably thick plywood sheets? That would give you a CNC machine capable of cutting out wood in essentially whatever dimensions you’d like, at reasonably low-cost. And that’s the idea behind [Bar]’s Maslow. It’s going to be a commercial product (we hope!), but it’s also entirely open source and indubitably DIYable.

[Bar] walks us through all of the design decisions in this video, which is a must-watch if you’re planning on building one of these yourself. Basically, [Bar] starts out like any of us would: waaaay over-engineering the thing. He starts out with a counterweight consisting of many bricks, heavy-duty roller chain, and the requisite ultra-beefy motors to haul that all around. At some point, he realized that there was actually very little sideways force placed on a sharp router bit turning very quickly. This freed up a lot of the design.

His current design only uses two bricks for counterweights, uses lighter chains, and seems to get the job done. There’s a bit of wobble in the pendulum, which he admits that he’s adjusted for in software. Motors with built-in encoders and gearing take care of positioning accurately. We haven’t dug deeply enough to see if there’s a mechanism to control the router’s plunge, which would be great to cut non-continuous lines, but first things first.

Taking the wall plotter into the woodshop is a brilliant idea, but we’re sure that there’s 99% perspiration in this design too. Thanks [Bar] for making it open! Best of luck with the Kickstarter. And thanks to [Darren] for the tip.

Running LISP On An ESP8266

LISP is a polarizing language. Either you love it or you hate it. But we’ll put aside our personal preferences to bring you a good hack. In this case a LISP environment running on an ESP8266. [Dmitry] is on the “love it” side of the fence — he’s been waiting for an excuse to code up a LISP interpreter for a while, and he found one in the ESP8266.

there-is-always-a-way-2Actually, [Dmitry] is running LISP inside JavaScript, which is itself presumably coded up in C, before it’s assembled to run on an ESP8266. (It’s turtles all the way down!) This means that he can piggy-back on JavaScript’s garbage collection and console handling and so on. After picking a suitably small LISP implementation (actually a Scheme dialect for those of you who know the difference), he went to work.

One weekend bled into the next, but he got the system running, connected to the network, and had LEDs blinking! In the end, he even managed to squeeze in some optimization for memory’s sake. Pretty cool, and because it takes advantage of an already complete system, it can even be made pretty useful. Not bad for a few weekends’ work!

And finally, if Lots of Irritating Silly Parentheses is your idea of a good time, but the wealth of computing resources available on an ESP8266 seem overkill, have a look at Microlisp, running on an AVR. Or go to the opposite extreme, and run a LISP OS on a Raspberry Pi. Whatever you do, don’t forget to close your parentheses! (We’re told that’s a traditional LISPer farewell.)