I bought several sets of E12 resistor sets on E-Bay from a supplier I will not name expect to say that he claims to "know" electronics. Tape mounted, not floor sweepings, looked fine at a good price.
Some problems with a circuit I was working on led me (after a couple of hours!) to check and may sure I'd used the right values. Measuring I found that several 47k resistors (yellow, violet, black, red) resistors were actually 56K! I went back to the tape mounted set that remained and found that the first 5 that remained were 56K, followed by 47K for the rest, all marked as 47k.
I asked my brother, who runs a small electrical equipment supply business, about this and he said that they were probably "run out" parts, pulled from a production run when they changed over values. Since the exact point of the changeover isn't known at the end, a portion of the run before and after the change is supposed to be pulled out and discarded.
Or sold on E-Bay I guess.... from now on I'm going to check each one before I use it.
Some problems with a circuit I was working on led me (after a couple of hours!) to check and may sure I'd used the right values. Measuring I found that several 47k resistors (yellow, violet, black, red) resistors were actually 56K! I went back to the tape mounted set that remained and found that the first 5 that remained were 56K, followed by 47K for the rest, all marked as 47k.
I asked my brother, who runs a small electrical equipment supply business, about this and he said that they were probably "run out" parts, pulled from a production run when they changed over values. Since the exact point of the changeover isn't known at the end, a portion of the run before and after the change is supposed to be pulled out and discarded.
Or sold on E-Bay I guess.... from now on I'm going to check each one before I use it.
I always measure them first on the tape and pick the ones i want, or is often the case building amps pick two matched resistors so i have the same value on both channels. Might be a little OCD but at least you know what your using..
One could read the value on the SMD resistor before placing it on the board. I suppose that would be sensible. It does get complicated when I select components from my store with resistors and capacitors of E36 values. The idents are rather small on resistors and non existent on capacitors.
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