One of the first things you learn in electronics is how to identify a resistor’s value. Through-hole resistors have color codes, and that’s generally where beginners begin. But why are they marked like this? Like red stop signs and yellow lines down the middle of the road, it just seems like it has always been that way when, in fact, it hasn’t.
Before the 1920s, components were marked any old way the manufacturer felt like marking them. Then in 1924, 50 radio manufacturers in Chicago formed a trade group. The idea was to share patents among the members. Almost immediately the name changed from “Associated Radio Manufacturers” to the “Radio Manufacturer’s Association” or RMA. There would be several more name changes over the years until finally, it became the EIA or the Electronic Industries Alliance. The EIA doesn’t actually exist anymore. It exploded into several specific divisions, but that’s another story.
This is the tale of how color bands made their way onto every through-hole resistor from every manufacturer in the world.
Continue reading “Why Do Resistors Have A Color Code?”
Nothing makes us feel more like we’re on Star Trek then saying “Computer, turn on desk light,” and watching the light turn on. Of course, normal people would have left the wake up word as “Alexa,” but we like “Computer” even if it does make it hard to watch Star Trek episodes without the home automation going crazy.
There’s a lot of hype right now about how voice recognition and artificial intelligence (AI) are transforming everything. We’ve even seen a few high-profile types warning that AI is going to come alive and put us in the matrix or something. That gets a lot of press, but we’re not sure we are even close to that, yet. Alexa and Google’s similar offerings are cool, there’s no doubt about it. The speech recognition is pretty good, although far from perfect. But the AI is really far off still.
Today’s devices utilize two rather rudimentary parts to provide an interaction with users. The first is how the devices pattern match language; it isn’t all that sophisticated. The other is the trivial nature of many of the apps, or — as Alexa calls them — skills. There are some good ones to be sure, but for every one useful application of the technology, there’s a dozen that are just text-to-speech of an RSS feed. Looking through the skills available we were amused at how many different offerings convert resistor color codes back and forth to values.
There was a time when building electronics meant learning the resistor color code. With today’s emphasis on surface mount components, though, it is less useful than it used to be. Still, like flossing, you really ought to do it. However, if you have an Amazon Alexa, it can learn the color code for you thanks to [Dennis Mantz].
Don’t have an Alexa? You can still try it in your browser, as we will show you shortly. There are at least eight similar skills out there like this one from [Steve Jernigan] or [Andrew Bergstrom’s] Resistor Reader.
Continue reading “Alexa, Sudo Read My Resistor! A Challenge For Hackers”
Cx5 is a strange material that’s a favorite of model makers and prop replicators. It’s kind of like a wax, kind of like a clay, and a little bit like a plastic. Now it’s a 3D printer filament. It looks very interesting for sculpted and highly detailed models, something the 3D printing scene hasn’t had yet.
So you want a CNC machine, right? Tormach makes a good one, and here’s what it takes to put a PCNC440 in your garage. This is an incredible amount of work and a great excuse to buy an engine hoist.
[Zemnmez] could find dozens of apps and webpages that would calculate resistor color codes for him automatically. What he couldn’t find is one that would do it in reverse – i.e. type in a resistor value and return the correct color code. He made this.
[aggaz] needed a way to connect multiple MIDI devices to his computer. The MIDI spec provides a neat piece of hardware for just this occasion – the MIDI thru box. The only thing you need to build a single MIDI thru box is an opto-isolator and a buffer. It’s easy enough to build, although the DIN5 jacks used for MIDI devices are pretty expensive nowadays. (FWIW- We get an invalid certificate error when loading this page but you should still be able to load it.)
AliExpress always has some interesting stuff on it, and [Ethan] found something very cool. They’re A8 CPUs found in the latest iPhone. Are they real? Who knows. I bought one, and you’re going to get pictures in another links post in a month or so.
The Game Boy Micro was released by Nintendo in 2005 and quickly became one of the coolest and most desired handheld consoles on the planet. You need only look at the eBay listings for the Micro as evidence of its desirability. [ModPurist] took an old DS Lite and converted it into a Game Boy Micro – same idea, larger package.
Here’s a tip from a wizened engineer I’ve heard several times. If you’re poking around a circuit that has failed, look at the resistor color codes. Sometimes, if a resistor overheats, the color code bands will change color – orange to brown, blue to black, and so forth. If you know your preferred numbers for resistors, you might find a resistor with a value that isn’t made. This is where the circuit was overheating, and you’re probably very close to discovering the problem.
The problem with this technique is that you have to look at and decode all the resistors. If automation and computer vision is more your thing, [Parth] made an Android app that will automatically tell you the value of a resistor by pointing a camera at it.
The code uses OpenCV to scan a small line of pixels in the middle of the screen. Colors are extracted from this, and the value of the resistor is displayed on the screen. It’s perfect for scanning through a few hundred through hole resistors, if you don’t want to learn the politically correct mnemonic they’re teaching these days.
Video below, and the app is available for free on the Google Play store.
Continue reading “Reading Resistors With OpenCV”
Need a quick and easy way to sort through a few hundred random resistors? You could do them one at a time by reading the color codes yourself… or you could get a machine to do it for you!
When [Robert] was faced with a pile of unsorted resistors he quickly decided he did not have the patience to sort them manually. So, he started by writing an Android app using OpenCV to detect and identify resistor color codes. The problem is, most phones have trouble focusing at short distances — and since resistors are so small, holding the phone farther back results in color rings only being a few pixels wide — not the greatest for image recognition!
So, he started again on his computer, using a cheap LED-lit webcam instead. He wrote the app in java so he could re-use parts of the code from the Android app. It seems to work pretty well — check it out in the following video! This would be perfect to pair up with your illuminated storage bin hack.
Continue reading “ReSCan — Automated Resistor Identification!”
If you’ve ever had to organize a bunch of resistors, you’ll know why [Anthony] created EESpeak. It’s a voice-controlled component look up tool that calculates a component value by listening to you read out color code bands.
In his demo video of EESpeak, [Anthony] reads off the color bands of several resistors whilst the program dutifully calculates and displays the value. [Anthony] also included support for calculating the value of capacitors and inductors by speaking the color bands, as well as EIA-96 codes for SMD parts.
In addition to taking speech input and flashing a component value on the screen, EESpeak also has a text-to-speech function that will tell you what a component without ever having to look at your monitor.
Even though the text-to-speech function seems a little cumbersome – it takes much longer for a computer to speak a value than to display it on the screen – using voice recognition to calculate component values is an awesome idea. With an extremely limited vocabulary the computer has to understand, the error rate of EESpeak is probably very low.
You can check out [Anthony]’s demo video after the break, and of course download the app on his blog.
Continue reading “Sorting Resistors With Speech Recognition”
[PT] tipped us off about a new way to screen bots from automatically leaving comments. Resisty is like CAPTCHA but it requires you to decipher color bands on a resistor instead of mangled text. This won’t do much for the cause of digitizing books, but if you can never remember your color codes this is a good way to practice. Resisty comes as a plug-in for WordPress, add it to your blog and for a geek cred +1.