The Engineer Guy Explains How MEMS Accelerometer Chips Work

There’s a good chance that you use a MEMS accelerometer every single day. It’s the small chip that let your smart phone automatically adjust its screen orientation. They’re great chips, and since they’re mass-produced you can add them to your projects for a song (if you can abide the tiny packaging). But we have no idea of how they are made and only a inkling of how they work. [Bill Hammack] has filled that knowledge gap with this explanation of how MEMS accelerometers are made and how they function.

Our base knowledge comes from the acronym: Micro Electro-Mechanical Systems. There’s something in the chip that moves (so much for solid state electronics; and it makes us wonder if these wear out). [Bill] includes a diagram in his video after the break which shows the silicon-based system that moves as it is affected by gravity. This changes the capacitive properties of the structure, which can be measured and reported to a microcontroller for further use. The structure is built using an intricate etching process which we never want to try out at home.

Looking for a project in which to use one of these devices? We’ve always been fond of this POV device.

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Automatic Capacitor Charger Lets You Have Fun With Sparks

[GranTotem] is delighted by the sparks put out when a capacitor is rapidly discharged. But he’s not impressed at the relatively slow process of connecting them to a power supply for a recharge. So he built this auto-charging station for his capacitors that provides a shockingly good time almost continuously. Check out the video to see what we mean.

We always like to see the guts of the project, and that’s why we chose this image for the feature. But when everything is properly seated in the project box [GranTotem] has managed to achieve a really clean look. There are two barrel jack connectors on the end, one for 16V and the other for 20V inputs. The lid of the enclosure hosts an on/off switch, adjustment knob, and two banana connector terminals. Once switched on, a relay connects and disconnects the capacitor from the power supply at regular intervals which are adjusted by the knob. Just connect a couple of probes to those banana terminals and let the sparks reign down.

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Prototyping An Advanced Inductive Charger

This is an advanced inductive charging system into which [David McIntosh] has put a lot of hard work. It uses the same coil-based concepts that we’ve seen in other DIY systems, but the game changer is a communications function that just isn’t found in home brew versions of the hardware. It lets the receiver (device being charged) give feedback to the transmitter by rolling another signal into the EM field being generated.

Do why would you need feedback? Well, if the two coils are not positioned well, the power produced on the receiving end can vary greatly. For instance, you may have the wrong voltage because the coils are not balanced. Or there may not be enough current to properly start charging. The feedback system is designed to let the sending unit change frequency to try to account for physical orientation, or to shut itself off if the charge is just not possible. This is done in expensive commercial devices, and that’s what [David] used as his model.

Scavenging From Consumer Electronics To Make A Flame-powered Phone Charger

[Gigafide] just finished building this flame-powered phone charger. The concept is not new. He grabbed a Peltier cooler and used the temperature differential between a flame and a heat sink to produce electricity used by the charger. If you search around here enough you’ll find plenty of candle-powered devices, and a few hacks that use a Peltier device in a bit more interesting way. But we really like his high-production value video, straightforward explanation of the concepts, and ability to source the components in consumer devices. We don’t think you’ll be disappointed by his video found after the break.

The Peltier device comes out of a USB drink chiller. It is supported by a metal stand made from electrical box covers and threaded rod. Underneath he’s using a gel fuel can used by the food industry, and above he’s got  CPU heat sink and fan. This setup puts out around 1.5V but he’ll need a boost converter to charge a phone with that. A single AA battery charger meant to power your phone in a pinch is perfect for this application.

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Brawndo Drinking Fountain – It’s Got What Geeks Crave!

brawndo fountain

If you’re tired of drinking mere water, like from the toilet, then you should definitely install a Brawndo drinking fountain. Apparently, in addition to being what plants crave, geeks also enjoy this futuristic beverage.

As with many hacks, this fountain started out with a broken piece of equipment – a water fountain. After searching unsuccessfully for a new pushbutton valve [Dave] and [Craig] decided to use a solenoid valve instead. Logically, they decided that if a new valve was needed, some new features to go along with it were also needed. Along with this valve, a peristalsis pump was installed to add flavoring to the water if Brawndo was selected (as opposed to toilet water).

The hack was finished off with some nice decals and a switch plate. As you may have suspected, the Brawndo fountain was custom made for a makerspace.  In this case Kansas City’s own Hammerspace. Be sure to check them out if you’re in the area!

Tron Costume Fits Nice And Snug

We’ve seen our fair share of Tron costumes and props, but much like [Sean-h] points out, they are usually pretty bulky and baggy. He’s gone a slightly different route by starting with a wetsuit instead of bulkier items like leather jackets. The lighting is done in the same manner we’ve seen before, copious amounts of EL wire and EL tape. The additional layers of this costume were made from foam, so they could be fairly form fitting as well.

[Sean-h] points out that there are some downfalls to his design. The wetsuit, while looking great, gets pretty hot while indoors and the foam layers have a tendency to detach if you move around too much. We think it looks great though. Good job [Sean-H]

Building A Sound Reactive EL Panel And Learning Something In The Process

We’ve seen a lot of builds using electroluminescent wire, usually in the realm of costumes and props. Unfortunately, most electrical engineers don’t deal with blinking and dimming EL wire and panels and any tinkerer trying to control electroluminescence doesn’t have a lot of resources on how to control EL stuff. [ch00f] wanted to fill this knowledge gap, so he build a sound reactive EL panel driver and learned a lot in the process.

Nobody really knows how electroluminescent wire and panels work on a molecular level, but [ch00f] did know that changing the direction of an electric field will cause the EL material to glow. Changing the frequency of this electric field will change the EL material’s brightness, so all [ch00f] had to do was make a variable-frequency EL driver – something that’s a lot harder than it sounds.

We won’t bore you with the details because we  couldn’t do [ch00f]’s write up any justice. We will skip to the end and tell you [ch00f] was able to make a sound reactive EL panel after a month of work that included making his own transformers and doing a whole bunch of math. You can check out the video of [ch00f]’s [Tony Stark]-esque EL panel after the break.

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