Configure ESP8266 Wifi With WiFiManager

March 18, 2017 by Al Williams 39 Comments

There’s no doubt that the ESP8266 has made creating little WiFi widgets pretty easy. However, a lot of projects hard code the access point details into the device. There’s a better way to do it: use the WiFiManager library. [Witnessmenow] has a good tutorial and a two-minute video (which you can see below).

Hard coding is fine if you are just tinkering around. However, if you are going to send your device away (or even take it with you somewhere) you probably don’t want to reprogram it every time you change access points. This problem is even worse if you plan on a commercial product. WiFiManager does what a lot of commercial devices do. It initially looks like an access point. You can connect to it using a phone or other WiFi device. Then you can configure it to join your network by setting the network ID, password, etc.

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Retrotechtacular: How Old Is The Remote?

March 16, 2017 by Al Williams 69 Comments

A few weeks ago we covered a (probably) bogus post about controlling a TV with the IR from a flame. That got us thinking about what the real origin of the remote control was. We knew a story about the 38 kHz frequency commonly used to modulate the IR. We’ve heard that it was from sonar crystals used in earlier sonic versions of remotes. Was that true? Or just an urban myth? We set out to find out.

Surprise! Remotes are Old!

If you are a younger reader, you might assume TVs have always had remotes. But for many of us, remotes seem like a new invention. If you grew up in the middle part of the last century it is a good bet you were your dad’s idea of a remote control: “Get up and turn the channel!” Turns out remotes have been around for a long time, though. They just weren’t common for a long time.

If you really want to stretch back, [Oliver Lodge] used a radio to move a beam of light in 1894. In 1896, [Marconi] and some others made a bell ring by remote control. [Tesla] famously showed a radio-controlled boat in 1898. But none of these were really remote controls like we think of for a television.

Of course, TV wouldn’t be around for a while, but by the 1930’s many radio manufacturers had wired remotes for radios. People didn’t like the wires, so Philco introduced the Mystery Control in 1939. This used digital pulse coding and a radio transmitter. That’s a fancy way of saying it had a dial like an old telephone. As far as we can tell, this was the first wireless remote for a piece of consumer equipment.

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Mechanical Music Maker Throws Stones

March 15, 2017 by Al Williams 10 Comments

When we think of a xylophone we envision hitting the keys from above with mallets. But this robot instrument launches stones from below to play a tune. [Niel] calls the device a Pinger and it is part of a Rock Band — all instruments using rocks.

Although the original post has “xylophone” in it, this musical instrument is technically a glockenspiel because it uses metal keys instead of wood. Either way, it’s a work of art; the instrument’s creator ([Neil Mendoza]) was participating in ~~Adobe’s~~ Autodesk’s Pier 9 artist-in-residence program when he built it.

The keys were cut using a water jet, a process not easily in reach for most of us. But you could make do with a different process in a pinch. On the face of it, fabrication seems simple, but there’s software to calculate the right size for the keys depending on the material. The cuts need to be precise to yield an in-tune instrument.

The circular part is laser-cut acrylic, acting as a base for each key. Below the plate there is a cylinder positioned in the middle of the bar which keeps the stone from getting away. When the solenoid fires, the stone flies up and strikes the key, creating a ringing tone but also adding to the body of sound with a rattle when it falls back down to the base. The entire thing is driven by MIDI, so it can play a lot of tunes besides the biographical “Here Comes the Sun” (since, apparently, the pebbles are out in the sun). Check that out in the video below.

This couldn’t help but remind us of another solenoid-driven xylophone — whose keys were machined out of aluminum stock. There’s also the multixylophoniomnibus.

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Google Machine Learning Made Simple(r)

March 14, 2017 by Al Williams 18 Comments

If you’ve looked at machine learning, you may have noticed that a lot of the examples are interesting but hard to follow. That’s why [Jostmey] created Naked Tensor, a bare-minimum example of using TensorFlow. The example is simple, just doing some straight line fits on some data points. One example shows how it is done in series, one in parallel, and another for an 8-million point dataset. All the code is in Python.

If you haven’t run into it yet, TensorFlow is an open source library from Google. To quote from its website:

TensorFlow is an open source software library for numerical computation using data flow graphs. Nodes in the graph represent mathematical operations, while the graph edges represent the multidimensional data arrays (tensors) communicated between them. The flexible architecture allows you to deploy computation to one or more CPUs or GPUs in a desktop, server, or mobile device with a single API. TensorFlow was originally developed by researchers and engineers working on the Google Brain Team within Google’s Machine Intelligence research organization for the purposes of conducting machine learning and deep neural networks research, but the system is general enough to be applicable in a wide variety of other domains as well.

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Robot Hand Goes Wireless

March 13, 2017 by Al Williams 7 Comments

We can’t decide if [MertArduino’s] robotic hand project is more art or demonstration project. The construction using springs, fishing line, and servo motors isn’t going to give you a practical hand that could grip or manipulate anything significant. However, the project shows off a lot of interesting construction techniques and is a fun demonstration for using nRF24L01 wireless in a project. You can see a video of the contraption, below.

A glove uses homemade flex sensors to send wireless commands to the hand. Another Arduino drives an array of servo motors that make the fingers flex. You don’t get fine control, nor any real grip strength, but the hand more or less will duplicate your movements. We noticed one finger seemed poorly controlled, but we suspect that was one of the homemade flex sensors going rouge.

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Pulse Oximeter Is A Lot Of Work

March 11, 2017 by Al Williams 24 Comments

These days we are a little spoiled. There are many sensors you can grab, hook up to your favorite microcontroller, load up some simple library code, and you are in business. When [Raivis] got a MAX30100 pulse oximeter breakout board, he thought it would go like that. It didn’t. He found it takes a lot of processing to get useful results out of the device. Lucky for us he wrote it all down with Arduino code to match.

A pulse oximeter measures both your pulse and the oxygen saturation in your blood. You’ve probably had one of these on your finger or earlobe at the doctor’s office or a hospital. Traditionally, they consist of a red LED and an IR LED. A detector measures how much of each light makes it through and the ratio of those two quantities relates to the amount of oxygen in your blood. We can’t imagine how [Karl Matthes] came up with using red and green light back in 1935, and how [Takuo Aoyagi] (who, along with [Michio Kishi]) figured out the IR and red light part.

The MAX30100 manages to alternate the two LEDs, regulate their brightness, filter line noise out of the readings, and some other tasks. It stores the data in a buffer. The trick is: how do you interpret that buffer? Continue reading “Pulse Oximeter Is A Lot Of Work” →

So Long, And Thanks For All The Crystals

March 11, 2017 by Al Williams 53 Comments

There was a time when anyone involved with radio transmitting — ham operators, CB’ers, scanner enthusiasts, or remote control model fans — had a collection of crystals. Before frequency synthesis, became popular, this was the best way to set an accurate frequency. At one time, these were commonly available, and there were many places to order custom cut crystals.

One of the best-known US manufacturers of quartz crystals still around is International Crystal Manufacturing (ICM). Well, that is, until now. ICM recently announced they were ceasing operations after 66 years. They expect to completely shut down by May.

In a letter on their website, Royden Freeland Jr. (the founder’s son), committed to fulfilling existing orders and possibly taking some new orders, raw materials permitting. The company started making products out of Freeland’s father’s garage in 1950.

Another big name that might still be around is Jan Crystals. We say might, because although their website is live, there’s not much there and the phone number is not quite disconnected but it is “parked.” There are also some posts on the Internet (where everything is true) indicating they are out of business.

Even if you didn’t do radio work, crystals are a staple in digital systems where an accurate clock is necessary and some types of filters, too. Of course, you can still get them, you just may not be able to get them made in the United States soon.

If you want to know more about the technology behind crystals [Jenny] has you covered. Crystals are one of those things that have not changed much in a long time, so you might enjoy the very 1960’s vintage U. S. Air Force training film below.

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