Resistor assortments - quantities of each value - Page 1
Forum section: electronics / general

author: Clear as mud
author_rank: Regular Contributor
timestamp: January 13, 2020, 08:28:30 am
content: It's the middle of the night here in the USA, but I can't sleep. Maybe after posting this I can go to sleep. The description said rants go in this section of the forum.The problem is resistor assortments. Everyone selling them these days seems to make the same fundamental mistake - they sell the same quantity of each value. For example, I bought an E24 assortment of resistors (I think 171 different values), from a supplier in Florida, and I got 100 of each value (they were 0805 SMT resistors, so not very large). But it's certain I'm going through some of the values a lot faster than others. For example, 1k is common to use, but when would I ever use 620k? So, really, the assortment should contain a whole bunch of 1k resistors, and fewer of the values that are rarely used.Now, back in the day, Radio Shack sold resistor assortments, and they came with different numbers of different values. For example, inEEVBlog 1240, Dave thumbs through an old Tandy catalog, and around 17:45 in the video, he comes to the page with a pack of 100 1/2 watt resistors. The small print is hard to read, but it appears to sayQuoteAnd I remember, probably a few years after that catalog came out, I went into a Radio Shack store and bought an assortment of 500 1/4 watt resistors. They were 5% tolerance, but included only the E12 values. The common values had quite a few, up to about 20 or 30 of each value, but the less common ones only had 4 or 5.Anyone remember how many of each resistor the 500 pack had? I haven't been able to find the information. I may have to go back and count how many of each value were in my old assortment, but I've used some of them, so I might not be very accurate that way.

author: david77
author_rank: Frequent Contributor
timestamp: January 13, 2020, 09:54:14 am
content: I'd say thats a problem with most companies selling components in assortments, the people running these companies are mostly clueless beancounters. They don't know what resistor values are commonly used and I guess it's easier and cheaper to put 100 each in the kit than to instruct the workers to count to other numbers.But in a way that is also a good thing, I strongly suspect doing it another way would be chaos. The pickers who assemble these component kits usually have not the first idea what it is they are picking from their bins. I see that everyday at work, we order 100 red banana plugs and get 100 rotary switches...

author: Ian.M
author_rank: Super Contributor
timestamp: January 13, 2020, 10:14:28 am
content: Rat shack's assortment quantities would have (mostly) reflected common usage at that time. Back in the day, 1K was pretty much the standard pullup for TTL logic. Now its usually 10K for CMOS logic. Similarly there have been considerable value changes for LED current limiting resistors as LED colours with higher Vf have become cheap and popular, and logic supply voltages have dropped. Even analog circuits have been strongly influenced by the trend of reducing supply voltages and power consumption.Also later on, they were notorious for selling two resistors in a blister pack for a ridiculously high price, so I wouldn't expect their later assortment quantity choice to be beneficial to anyone except their shareholders!Therefore IMHO, their assortment quantities are of historical interest only, and rather than wasting time trying to work out how many were in your 500 assortment, you'd be much better off simply ordering replacement stock of whichever individual values you are using the fastest on your next order from a major distributor, or going back over designs of stuff you've built and processing the BOMs to extract total values and quantities used.

author: Mr Evil
author_rank: Regular Contributor
timestamp: January 13, 2020, 04:54:11 pm
content: I'd say it's just as much a problem with the way people choose which value to use. Round decimal values are used a lot because they have a lot of 0s in them, which people like, but there's littlepracticalreason to use them. If you choose optimal values, they will be all over the place (perhapsmore likely to contain the digit 1 than other digits, but that's already accounted for in the logarithmic scale of the E series). Personally, if there's no specific value that's obviously best, then I choose them based on how much I like the colours of the stripes, which means a lot of 75k.

author: all_repair
author_rank: Frequent Contributor
timestamp: January 13, 2020, 05:09:15 pm
content: My view on the assortment usage is the inversed. They are best for prototyping, rarely used and should be filled up most of the time so when one particular value is heavily used, there shall be a sticker on that value to state "more available at drawer X".

author: German_EE
author_rank: Super Contributor
timestamp: January 13, 2020, 05:17:23 pm
content: I have a kit of 200 of each value from 1 ohm to 1M ohm in 0603, I might use all of the contents before I go toes-up but probably not. I also have a 4000 reel of 1k ohm, a 4000 reel of 10k ohm and a 4000 reel of 100n 50V capacitors. Each of these reels were thirty euro each and I will never run out.