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.

# ReSCan — Automated Resistor Identification!

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.

# Sorting resistors with speech recognition

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.

# Are you human? Resistor edition

[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.