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How familiar are you with colour codes?

21 Dec 2015  | Michael Dunn

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Is learning resistor colour codes still a big deal for young whippersnappers of today?

I remember my earliest youthful forays into electronicland: what are those colourful bands on those little cylindrical parts? Ah, they are resistor values. My local Radio Shack sold me a cool little "calculator" to decode them. For 79¢ no doubt.

Sadly, that calculator seems long gone. It was a cardboard contraption, with three toothed discs. Through little cutouts in the outer cardboard envelope, I could match colour to number by rotating the discs.

I don't recall how long I carried this with me everywhere, merrily twiddling the discs and reading off colours or values. Blue-yellow-red. Ahhh. 6,400Ω. It didn't matter that this value was non-existant. I learned my colours soon enough, and the discs got relegated to a dusty drawer somewhere. Rosebud.

Flash quiz: What values are the following resistors?

Put your answers below if you like.

Of course, leaded (that's "leeded," not "ledded") colour-coded resistors are far from extinct, as anyone who practises the electronics hobby will be aware. But in the real world, they are approaching extinction. Tell me, o youthful grad: Was it taught? If you have not done the hobby thing, do you know your codes? Or is the knowledge slipping away, like cursive writing and knowing how to use a dial telephone?

If resistor codes have become boring and passé, introduce yourself to the Brave Old World of capacitor colour codes. There was such a fascinating variety back in the days of strange looking UFO capacitors, made of exotic things like paper and mica and sealing wax. OK, just regular wax really.

And no need to stop there. Inductors, diodes, and doubtless other parts can be found with colourful banding, dots, splotches, and swatches. But that's an exercise for the student.

About the author
Michael Dunn has been messing with electronics almost as long as he's been walking. He got his first scope around age 15, and things have been going downhill ever since. The scopes now vie with wine racks, harpsichords, calculators, and 19th century pianos for space. Over the years, he's designed for the automotive, medical, industrial, communications, and consumer industries, as both freelancer and employee, working with analogue, digital, micros, and software. Since 2000, he's run the TekScopes Yahoogroup, now with over 5,000 members, and he was previously editor-in-chief of Scope Junction.

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