01R vs 1R0 - Page 1
Forum section: electronics / beginners

author: Rick Law
author_rank: Super Contributor
timestamp: November 05, 2015, 10:10:02 pm
content: Is there any difference between 01R vs 1R0 on the SMD? They are both 1ohm according to nomenclature.I see both on a PC server motherboard. That led me to think it may not be just different manufacturer as the server-board guy likely purchased the 01R and 1R0 from the same maker.

author: tron9000
author_rank: Frequent Contributor
timestamp: November 05, 2015, 10:13:42 pm
content: give it a test with the ol' DMM

author: Monkeh
author_rank: Super Contributor
timestamp: November 05, 2015, 10:44:12 pm
content: Quote from: Rick Law on November 05, 2015, 10:10:02 pmI'd be willing to bet the P&P (or P&Ps) had multiple reels of 1R. They place A Lot™ of parts.

author: Maxlor
author_rank: Frequent Contributor
timestamp: November 05, 2015, 10:49:21 pm
content: There's a difference in the accuracy of the parts I'd guess?

author: TimFox
author_rank: Super Contributor
timestamp: November 05, 2015, 11:29:39 pm
content: Leading zeros are not significant.Trailing zeros are significant.

author: Rick Law
author_rank: Super Contributor
timestamp: November 06, 2015, 07:02:29 pm
content: Quote from: tron9000 on November 05, 2015, 10:13:42 pmWith just it expected to be around 1ohm, testing in-circuit is likely not meaningful. This one looks like an 0603 or smaller on a still-in-used motherboard. It is easy to loose something that small when removed. I have yet to find a 0805 green LED that I knew for sure felt off the table and by now probably in LED heaven.These days, I scotch-tape SMDs down on the table top and only remove it from the scotch-tape covering when I am fully ready to solder that specific SMD.Quote from: TimFox on November 05, 2015, 11:29:39 pmThis is a good thought.* 01R is 1ohm with 1-digit accuracy.* 1R0 is 1.0 ohm with 2-digit accuracy.Unless/until another reason pops up, I will take it as 1 or 2 digit accuracy, I suppose. But I am still uncomfortable with that since accuracy is typically specified as 1% 5%... This is too esoteric even for my curiosity.

author: fivefish
author_rank: Frequent Contributor
timestamp: November 06, 2015, 08:07:11 pm
content: Who still uses 5% resistors? It's not the 80s anymore, 1% can be bought for $5.00 for 200pcs. They're so cheap nowadays.I only use 1% or better now in all my projects except if a value is OUT OF STOCK and I just want to get the project going, then I'll buy the 5%.

author: Rick Law
author_rank: Super Contributor
timestamp: November 06, 2015, 08:46:09 pm
content: Quote from: fivefish on November 06, 2015, 08:07:11 pmre: "Who still uses 5% resistors?"Yeah, I agree with what you said. Failing to find any difference between 1R0 vs 01R, I consider 1 ohm vs 1.0 ohm as aplausible explanationfor now.Quote from: Monkeh on November 05, 2015, 10:44:12 pmThis is also a very likely explaination in my mind. It could be just manufacturers labeling identical stuff differently. AsMonkehsuggested, it could be there was a wheel change between R5 and R36 (I am making the resister number up, I am not going to re-open the server just to re-read the resister number printed on the PCB).

author: m98
author_rank: Frequent Contributor
timestamp: November 06, 2015, 09:36:11 pm
content: Quote from: fivefish on November 06, 2015, 08:07:11 pmEven in high-end products you won't waste money on not needed accuracy. Why would you waste more than one cent per resistor just to have for example an 1% accurate pull-up?

author: fivefish
author_rank: Frequent Contributor
timestamp: November 07, 2015, 02:12:32 am
content: Quote from: m98 on November 06, 2015, 09:36:11 pmAnd I don't think manufacturers would waste an entire PNP feeder to load a 5% resistor just to save one cent for a pull-up resistor using your example, they'll just use other existing resistor values, even if it's 1%.In the same way that re-using resistor values rather than waste an entire feeder to load a different value... i.e. just load a single 10K reel on the feeder, and design the board to use (2) 10K resistors in parallel, rather than using a separate 10K and 5K reel of resistors.

author: logictom
author_rank: Unknown
timestamp: November 07, 2015, 04:48:38 am
content: Quote from: fivefish on November 07, 2015, 02:12:32 amSurely this is a toss up between how many reels are required for the run therefore how many runs through a pick'n'place vs the cost of adding two parts rather than one, board space taken up, number of boards run, etc, etc - it comes down to design/manufacturer specifics.I guess there's rules of thumb but how could you generalise it one way or the other?

author: m98
author_rank: Frequent Contributor
timestamp: November 07, 2015, 09:56:16 pm
content: Quote from: fivefish on November 07, 2015, 02:12:32 amSure, that depends on the application. But often you won't need any 1% resistors in a (digital) circuit.

author: SeanB
author_rank: Super Contributor
timestamp: November 08, 2015, 02:48:50 pm
content: Quote from: m98 on November 07, 2015, 09:56:16 pmTrue, but the manufacturer might already have the part in a feeder on the machine for another job, so it makes sense to simply use it as it meets the required spec. The particular board might only be a small run in amongst a larger run of boards, so minimising the number of feeder changes between jobs is a good thing to save wear on them, plus the cost difference between the parts might be zero. You often design a board and component layout based on a particular manufacturer's standard part feeder list, so that you do not pay a rereeling fee to have a part placed in a feeder just for you.