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Author Topic: Genius behind resistors stripe code and electrolytic cap wire length? [rant]  (Read 2961 times)
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I have two rants behind these electronic component 'conventions'.

First are resistors and their stripe coding. The bain of my existence. You get one mixed pile of resistors and you are gonna waste your time looking for the one you want especially if you have to de-code the stripes or individually measure the reading. Isnt it more logical to print the numbers of their resistance on them instead of some coded stripe (like they do for say capacitors). Even if you are a seasoned veteran in resistor stripe reading, its still a pain. And you are likely to forget the coding convention if you dont read resistors on a daily basis also. Its unnatural for new and even moderately seasoned folks who have to refer to the chart. Otherwise, for those just picking and reading off the resistance off a multimeter, its downright a PITA.

Its just so unnatural. Why dont they make the convention of printing the number on the resistors or at least have the numerical value along with the stripes? So what is the genius reasoning behind the stripe coding convention?

Second are electrolytic caps. LEDs have one longer arm than the other. Makes sense; its polar and its hard to tell which one is which so make one length longer. OK. Schottky diodes also have polarity, but they mark the polarity on the packaging while the lead length remains the same on both ends. Makes sense. Now, electrolytic caps. These have both marks to tell you the polarity, as well as having one lead longer than the other. Why? Is it not overkill? What is the genius behind this convention?

Please enlighten me.
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2 reasons for the resistor:
1) it is easier to produce a stripe coding printer than a text printer.
2) It doesn't matter how the resistor is soldered, the rings are always visible. (also from a distance)
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you can get resistors with numbers on them, though its just as frustrating to read microprint. Caps may be overkill, but an LED wont explode and catch fire if you hook it up backwards. Also not all caps have the leads clipped in that way.
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drawback - Colour blind Electrical Engineers cannot read the stripe coding. -

So lets invent something new! the most common Colour Blindness is red-green so I propose to make the Green stripe twice as width as the red one.

Now we still have the problem of total blind Electrical Engineers,.... => flat resistors with braille numbers on them?
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 I'm thinking you complain too much.  smiley-grin
Wait to you get as old as me and you can't even read the writing without tons of extra lighting and a big magnifying glass. As an aside I always take a resistance measurement on any resistor I use before soldering it into a circuit, trust me It's worth the extra time expended.  smiley-wink

Lefty
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Even if you are a seasoned veteran in resistor stripe reading, its still a pain. And you are likely to forget the coding convention if you dont read resistors on a daily basis also.

Seasoned veterans read 'em like a second language, at least the more common values. The less common only take a couple seconds longer. Brown-Black-Red is seen as a single word or piece of information that means 1000Ω, not as three different digits to decode. Yeah it probably comes from reading them on a daily basis for years on end. Good rant tho! smiley-grin

Oh, there are dirty mnemonics that may help in remembering the code smiley-eek-blue
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Wait to you get as old as me and you can't even read the writing without tons of extra lighting and a big magnifying glass. As an aside I always take a resistance measurement on any resistor I use before soldering it into a circuit, trust me It's worth the extra time expended.  smiley-wink

I'm with Lefty on this one. I can't read the damn things any more without my magnifying glass in my hand. Even chips with their part numbers in dark gray on a slightly darker gray background are a pain.
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Quote
Even chips with their part numbers in dark gray on a slightly darker gray background are a pain.

I have a magnifier-app on my phone that can negative the colours which has been quite helpful several times for difficult to read text.
It would be superb If I could remap the colour thresholds with it, like when you make a B&W scan, Think I'll mail the developer...smiley
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i think the lead lengths on the electrolytics might be for pick and place machines ?

But they still have to mark the polarity, ( for instance the assemblers I use, preform all the components and cut to length before hand assembly )

The real hassle now is that I have found some wonderful bright LEDs,   the long leg is +  anode,  but so is the flat on the rim, and so is the larger part of the die, both of which are normally - cathode.

When I queried this with my supplier i China, she said they call them the reverse polarity type !

As for chip numbers, the good old days had the numbers printed white, but I think they laser print them now, and often if I cant read it I take a shot with the digital camera, and blow it up on the viewfinder !

I never have to think of the colour code on resistors after 55 years I know them by looking, until my main supplier decided to just sell 2% tolerance or whatever, so now they have the extra stripe, so I am with you Lefty, and always check with my meter.
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i think the lead lengths on the electrolytics might be for pick and place machines ?

not the ones we use, caps come on a paper tape and the leads are cut pretty close to that so the machine can use it, and AFAIK the leads are the same length on the tape
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You get one mixed pile of resistors and you are gonna waste your time looking for the one you want especially if you have to de-code the stripes or individually measure the reading.

This might be part of your problem. Why are all your resistors in a pile, instead of organized by value?
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not the ones we use, caps come on a paper tape and the leads are cut pretty close to that so the machine can use it, and AFAIK the leads are the same length on the tape

Thats true,  I was thinking about the big electrolytics,  but for the life of me I can't remember if they had different length leads in the old days -  but then again a lot of them were axial then, before PCBs.

To save space ,for my R&D bench components, I have resistors, caps and zeners in the same 64 drawers , as some examples

 less than 1 ohm and 1 nF in the first drawer,   
3R3 with 3n3
100R with 100nF
1K with 1 mF
 4.7K with 4.7mF and 4.7 volt zeners ( and 5v regulators )
1M with 1000 mF

It saves trying to read them, but I still measure the resistors anyway....

Its also only 64 drawers to check for restocking


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I'm hopeless with colour, always have been and therefore I've always measured unless it's really obvious.

Fortunately almost all my electronics is uC related and as such I only need two resistor values, 10k for pullups and 1k for LEDs. That really helps  smiley

_____
Rob
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Yeah, I bought a strip of 500 of each, and each time I need a new one I just get it off the strip. $10 each (strip). And that was for 1% ones. I'm not going to waste an hour to save 5 cents.
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Back in 1965 my Dad gave me a big bag of resistors and a small card with the colour code on them.
I set to it putting them into piles of values. By the time I finished I knew the colour codes and threw away the card. I have never forgotten them despite going for months at a time now not reading them as most of my work uses surface mount.
As others say you don't translate the colours one by one, you just look at it an you know it's value.
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