Talking resistor calculator speaks component values

If there’s one thing that will surely blind us, its reading resistor color bands. It doesn’t help that red looks exactly like orange, brown and black are indistinguishable, and different component manufacturers – for some reason – don’t use identical paints for coding their resistors. [Jeff] over at Gadget Gangster has been having the same problem, so he built a talking resistor calculator to speak resistor values to him.

The electronics part of the build is extremely simple with just an MCP3208 ADC providing 12 bits of resolution. The software side is where this project really shines. [Jeff] used a Gadget Gangster QuickStart board housing a Parallax Propeller. With 8 cores running in parallel the Propeller is more than enough to run [Phil Pilgrim]‘s software speech synthesizer. When a resistor is connected to the two alligator leads, the Propeller goes through a lookup table and finds a resistor value matching the number coming from the ADC. From there, it’s just sending a string of phonetic text to the speech synthesizer object.

Even though text-to-speech chips have been around for decades now, [Jeff] chose to build his speech synthesis tool with software. It may just be a testament to the power in the Propeller microcontroller, but anything that keeps us from squinting at resistor color bands is alright by us.

A papercraft resistor calculator from Adafruit

The Adafruit blog just posted a neat papercraft resistor calculator. If you haven’t yet learned the horribly offensive mnemonic for resistor color codes, now’s your chance to have a cheap and portable resistor value reference.

This papercraft resistor calculator is the latest in the family of Circuit Playground tools that include a fabulous electronic reference app we reviewed some months ago. Instead of an Android or iOS device, the papercraft resistor calculator runs on its own mechanical computer; a series of four printed disks and some paper fasteners.

If you’d like to print out your own resistor calculator, Adafruit put up the PDF on GitHub and posted the Illustrator file on Thingiverse for easy editing. It’s not the old-school cool of a slide rule, but we could easily see this resistor calculator being useful if you’re ever lucky enough to teach electronics to children. At least then you won’t have to share that offensive mnemonic.