Author: Elliot Williams

1432 Articles

ESP32 Modules Popping Up Everywhere, In Stock Almost Nowhere

November 2, 2016 by 46 Comments

We know what it’s like to wait for newly released electronic parts. Clicking refresh every day at your favorite online retailers, reading reviews published by the press who got preview units, and maybe even daring to order implausibly cheap devices from foreign lands. The ESP32 has many of us playing the waiting game, and we’ll level with you — they’re out of stock most places. But, if you look hard enough you can find one. At least, you could find them before we wrote this quick roundup of ESP32 hardware. If hearing about parts that are just out of reach is your sort of thing, then read on, you masochist!

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FingerRing Is Simplest Multichannel Mixer

November 1, 2016 by 16 Comments

It’s hard to make an audio mixer with any less technology than FingerRing (YouTube video, embedded below). We’re pretty sure that [Sergey Kasich] isn’t going to get a patent on this one. But what he does get is our admiration for pushing a simple idea far enough that it’s obviously useful.

The basic idea is transmitting signals using the human body as a conductor. What [Sergey] does is lay out multiple sound sources and sinks on the table, and then play them like a mixer made musical instrument. Pressing harder reduces the resistance, and makes the sound louder. Connecting to two sources mixes them (in you). Watch the video — he gets a lot of mileage out of this one trick.

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What’s New, ESP-32? Testing The Arduino Library

October 31, 2016 by 30 Comments

In case you missed it, the big news is that a minimal Arduino core is up and working on the ESP32. There’s still lots left to do, but the core functionality — GPIO, UART, SPI, I2C, and WiFi — are all up and ready to be tested out. Installing the library is as easy as checking out the code from GitHub into your Arduino install, so that’s exactly what I did.

I then spent a couple days playing around with it. It’s a work in progress, but it’s getting to the point of being useful, and the codebase itself contains some hidden gems. Come on along and take a sneak peek.

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Put That Amateur Radio License To Use On 915 MHz

October 31, 2016 by 106 Comments

Amateur radio enthusiasts in the US will be interested in Faraday, an open-source digital radio that runs on 915 MHz, which amateur radio enthusiasts may know better as the 33 cm band.

You can transmit on 915 MHz without a license (in the US), taking advantage of the Industrial, Scientific, and Medical (ISM) exemption. This means that there’s commodity hardware available for sending and receiving, which is a plus. But you can’t do so with any real power unless you have an amateur radio license. And that’s what makes Faraday interesting — it makes it very easy to transmit and receive digital data, with decent power and range, if you’re licensed. The band is currently under-utilized, so go nuts!

The hardware design and documentation is online, and so is the firmware. The founders of the project would like you to build out a big network of these devices, possibly meshing them together. Our only regret is that the 33 cm band is only really open for use in the US, both with a license and without. Of course, there’s very little the Faraday team can do about that.

We’re no strangers to digital-mode amateur radio around here. But if you’re an amateur who hasn’t played around with digital modes yet, this might be a good way to get your feet wet.

Thanks to [Daniel] for the tip!

Projection Mapping In Motion Amazes

October 30, 2016 by 23 Comments

Projection mapping is pretty magical; done well, it’s absolutely miraculous when the facade of a building starts popping out abstract geometric objects, or crumbles in front of our very eyes. “Dynamic projection mapping onto deforming non-rigid surface” takes it to the next level. (Watch the video below.)

A group in the Ishikawa Watanabe lab at the University of Tokyo has a technique where they cover the target with a number of dots in an ink that is only visible in the infra-red. A high-speed (1000 FPS!) camera and some very fast image processing then work out not only how the surface is deforming, but which surface it is. This enables them to swap out pieces of paper and get the projections onto them in real time.

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Build The Simplest Bipolar Power Supply

October 29, 2016 by 46 Comments

How many integrated circuits do you need to build up a power supply that’ll convert mains AC into a stable DC voltage? Would you believe, none? We just watched this video by [The Current Source] (embedded below), where he builds exactly that. If you’re in the mood for a very well done review of diode bridges as well as half- and full-wave rectifiers, you should check it out.

First off, [TCS] goes through the basics of rectification, and demonstrates very nicely on the oscilloscope how increasing capacitance on the output smooths out the ripple. (Hint: more is better.) And then it’s off to build. The end result is a very simple unregulated power supply — just a diode bridge with some capacitors on the output — but by using really big capacitors he gets down into the few-millivolt range for ripple into a constant load.

The output voltage of this circuit will depend on the average current drawn, but for basically static loads this circuit should work well enough, and the simplicity of just tossing gigantic capacitors at the problem is alluring. (We would toss in a linear regulator somewhere.)

Quibbling over circuit designs isn’t why you’re watching this video, though. It’s because you want to learn something. Check out the rest of his videos as well. [TCS] has only been at it a little while, but it looks like this is going to be a channel to watch.

https://www.youtube.com/watch?v=0iDCsrMM7M0

Living Off The Grid, On Water Power

October 29, 2016 by 33 Comments

When you think of living off the grid, you often think of solar power. But if you’ve got a good head, and enough flow, water power can provide a much more consistent flow of electrons. All it requires is a little bit of engineering, epic amounts of manual labor, and some tricks of the trade, and you’ll have your own miniature hydroelectric power plant.

[Homo Ludens], the playful ape, has what looks like a fantastic self-sufficient home/cabin in a beautiful part of Chile. His webpages are a tremendous diary of DIY, but the microhydro plant stands out.

You might expect that building a hydro plant involves a lot of piping, and trenching to lie that pipe in, but the exact extent, documented in many photos, is sobering. At places, the pipe needed to be bent, and [Homo Ludens] built a wire-mesh pipe heater to facilitate the work — with the help of a few friends to weigh the pipe down at either end and create the bend. The self-wound power transformer is also a beauty.

There’s a lot more detail here than we can possibly get into, so go check it out. And if you’re in the mood for more hydro, we’ve recently run a writeup of a less ambitious, but still tidy, project that you should see. Or you could just rip apart an old washing machine.

Thanks [Patrick] for the great tip!