Octopart Pocket Electronics Reference PCB | Hacker News Reader

Octopart Pocket Electronics Reference PCB

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I bought a set of these a few weeks ago.

https://www.tindie.com/products/NsN/pcb-color-sample-set/?pt...

This is lovely.

One gentle suggestion for version 2 is conversions between pico, nano, and micro farads, and the capacitor codes used for these. Because even though it's easy to do it's still nice when you're feeling cognitively challenged to have a cheet sheet.

Thanks Dan! Maybe if this one goes well I'll get to do a sequel :)

Hmmm, meybe i'm getting this wrong, but... Isn't a color code too basic to be in a card in your pocket?

I mean, c'mon, i haven't used color codes since High School about 17 years ago and i still remember how to decode them. It's not that hard.

i feel that consulting a table is more time consuming that knowing how to decode it... Usually while working with prototyping you end up with lots of resistors, and i can't see someone checking each one at the time against a table to reveal it's value...

But maybe i'm getting it all wrong, someone?

If you're breadboarding a lot, or manually stuffing printed circuit boards, or otherwise doing manual assembly in some way, you quickly learn to read most common ranges of values on sight. Maybe some people like to keep a reminder around for when you encounter weird values, or when troubleshooting.

I need to color-code a resistor a few times a year. To do so, I usually consult the table on the wall in our electronics shop or just grab an ohm-meter.

If I needed to do it daily, I'd get real good real fast.

Like the SM footprints, but I'm not sure I see the point of the resistor color code chart these days (If I do spec a through hole resistor, 99% of the time it'll be a 1%).

Thanks joe! Yeah, sadly through hole seems to be going away on the whole, but the color codes are still used often by some people, especially while breadboarding or prototyping. I actually referred to a prototype of the card myself while designing a board a few weeks ago:) so some people will likely find one side or the other more useful. Fortunately we've designed the card to be useful in a good variety engineering contexts!

Not sure I understand - Vishay[1] MRS25 resistors are 1% and use a colour code. (http://www.vishay.com/docs/28724/mrs16m25.pdf)

They're generally pretty nice as resistors go. Do you spec better than that?

[1] I used these when they were Philips, which shows how long it is since I was doing this stuff.

The 1% series has an extra value band, which throws off their multiplier. Example: 1k 5% is brown black red (gold), but 1k 1% is brown black black brown (brown).

We do use a few 0.1% values in some cal equipment--about $1 each!

Most SMT resistors use a number code. Also, colorblind people.

This is way better, too bad it's over. :(

http://www.pozible.com/project/31806

Does "Set of Reference PCBs" mean four for $32.00?

edit: nevermind, I scrolled down far enough to find it.

I prefer using a multi-meter. That might be something to do with being colour-blind though.

That's a pain-in-the-butt way to find the one resistor you need in a pile of fifty. Even though you are color-blind, that's just red and green, so you too can say to yourself "blue, blue, I need two blue stripes..."

That's a weird mis-characterisation of what it means to be colourblind. It's one of the discriminations that's still legal in England - electronics companies are allowed to not employ people with colourblindness because of the lack of suitable 'reasonable adjustments' and the need to have colour vision for a lot of electronic stuff.

Also, any resistors not in a pcb should be in a nice drawer with a neat label; any resistor in a circuit could give misleading values when multimetered because it's in a circuit.

That's a weird mis-characterisation of what it means to be colourblind.

I thought male pattern colorblindness (far and away the most common type) simply means the inability to distinguish green from red, not total lack of color vision. Hence why I would expect you could still locate resistors with blue bands.

any resistors not in a pcb should be in a nice drawer with a neat label

"Should" being the operative word here. If that always happened, we wouldn't have bothered to give resistors identifying marks.

> If that always happened, we wouldn't have bothered to give resistors identifying marks.

Yes we would, because we need to know what that resistor is when it's in a PCB. We can't measure it because it may be in parallel with other resistors.

> Hence why I would expect you could still locate resistors with blue bands.

Can you identify what the colours of this image should be? (Ignoring the massive clue in the filename.) :-p

(https://en.wikipedia.org/wiki/File:Rainbow_Deuteranopia.svg)

That's for a severe form of the most common form of color-blindnes.

(https://en.wikipedia.org/wiki/Color_blindness#Classification)

Yes we would, because we need to know what that resistor is when it's in a PCB

Why couldn't we just label the resistor with silkscreen? We already decided labeling their drawer was better than labeling the resistor, so why not apply the same to the PCB? Easier to read silkscreen than color bands anyway, right?

Can you identify what the colours of this image should be

I said blue. Notice the blue is quite easy to spot in the image you linked. Of course it would still be a pain to try to find the 10k resistors by color, yes, I know that. But at least the color bands wouldn't be totally worthless.

> Why couldn't we just label the resistor with silkscreen? We already decided labeling their drawer was better than labeling the resistor, so why not apply the same to the PCB? Easier to read silkscreen than color bands anyway, right?

Some resistors are labelled with silkscreen. Those resistors are expensive 1%, 0.1%, or 0.01%.

For run of the mill resistors it's cheaper to use colour coding. Also, when assembling a PCB it's good practice to keep the codes visible. That takes extra time for human operators. I don't know how machines do it for conventional components.

Labelling the PCB is important. There's a space marked R1, and a parts list telling us what R1 should be. There's a resistor in that space. How do we know what that resistor is? We read the color code, or the marking on the device.

There could have been a mistake at the resistor making factory, so we have a goods-in inspector who does some checking of the goods coming into the factory, and we buy from quality vendors and quality manufacturers. We hope the ISO 900x accreditation means something; we hope the certificates of conformity mean something.

Unfortunately it is rarely that simple. For example I can easily spot 'pillar box' red and have no difficulty telling it apart from 'snot' green. In fact, its only in strange or low lighting that I generally have a problem telling red and greens apart. Green, Orange and Yellow; Purple, Pink and Blue; Red and Brown all can occasionally catch me out.

The effect of colour-blindness can also vary hugely from person to person. Even when they share the same type of colour-vision impairment.

Personally, I believe I tend to avoid relying on information coded in colour through habit, even when I can identify with reasonable accuracy the colours involved. Just as someone who is left handed will avoid complex tasks with their right.

Any resistor in the pile will do, because they're all the same value. Don't put different values of resistors (especially 5%ers) in the same pile :P

It's fun, but I'm not sure what it's for as I can look up these things on the internets if I forget. Is this just an executive engineer gadget?

It would be a good thing for my students to have in their kits. I try to get them to make something similar for SMT footprints every year (to print out on paper) with varying amounts of success. It is easy to get confused on different size designations (QFP, TQFP especially), and there is not a lot of utility in making people memorize stuff like this.

Package types are not size designations. Pin count & pitch matter more than QFP vs. TQFP, and the dimensions of one manufacturer's TQFP can easily be different from an others, so the datasheet is key.

Yes, for designing a product people must refer to a datasheet.

But when discussing things it's nice when someone can correctly say "TQFP", or when they see a choice of two ICs and you say "It's the QFP one" and they can pass that tube over.

You're correct, but you missed the point. I should have said QFN not QFP, and I should have been more precise. A QFN looks and is superficially very similar to a TQFP. If you look at an example like the PIC18F26J50, you'll notice that it is available in either a 44QFN or a 44TQFP. If you then look at either footprint in a layout editor or gerber viewer you'll notice that they are visually very similar in size and general appearance (and the pinout is almost the same). It is quite easy to confuse the two even by yourself, much more so if you are coordinating the efforts of several people (engineer, CAD operator, purchasing agents, etc.)

You have production staff in training on minimum wage on a production line.

Those people don't get Internet access.

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