Surface Mount Resistors with Values

the 0603s we use have numbers, I think they are from digikey don't have a reel here so I can't tell anymore specific what kind they are

-Lasse

Sorry, I wasn't clear. Digikey sells a bazillion different resistors, only some of which are marked. I was looking for manufacturer/series, so I limit my Digikey selections appropriately.

r.

I got that, thats why I said I don't have a reel right here, if I had I would have told you what kind it was :P

-Lasse

Tim, It looks to me that it depends on the values, somewhat. I have been buying all Rohm (Why? just because... ) and pretty much all the same series. Some parts are labeled, especially two significant digit parts, but some aren't, which I suspect are all three significant digit parts. Looks like they only have room for three characters on them! ;-)

Charlie

I know that at one point about six or seven years ago I assisted the EE department at my then-employer with searching out all of the marked series of resistors that we could get from Digikey. They were generally about 10% more, and damned convenient in the lab compared to looking at all the anonymous black things that may or may not have been tweaked in value by some dedicated and/or desperate EE.

ser.

s,

s,

Almost all my resistors are marked and none of my caps are. Fortunately, I only use limited set of caps and they usually come with slightly different colors or sizes. For example: pink 0402 18pF, grey 0602 0.1uF, brown 0602 1uF, 0805 4.7uF and 1210 22uF. I put them in Serial or Parallel to avoid other values if necessary.

Ok, another story from the trenches (and it ain't even day appropriate!)

We ordered 100 production boards of the rainbow color reader, and they came in late wednesday. Yesterday, I put the first six together to test, and the LEDs worked, the right values were being determined, but NO SPEECH!

I had done some tweaking in the software, so assumed I had messed something up. Checked a few things, finally went back to a known good version of the software - still no sound!

Grabbed a second unit, programmed it and tested - no sound!!!

Pulled out a not yet built board, and started verifying the connectivity... maybe I messed something up on the gerbers or something. Nope, everything connected correctly.

Pulled out the o-scope, and started tracing the signal. Found PWM output from the mcu, traced it through the circuit, and found it suddenly disappeared at one node. Finally, after a lot of other dead ends, replaced the cap attached to that node. (Did I mention I don't have an LCR meter?)

Better, I now could barely hear the speech output. Kept looking, replaced the next two caps, and everything worked fine.

Notified the assembly folks, and they assured me that all the parts used were exactly what was on the BOM. Even sent me a photo of the lables on the reels. I took another unit, and replaced the two caps that were the same value (2.7nF) and it worked as well. Emailed them, and asked them to test that reel.

Reel was labeled 2700pF, measured value .9uF! Digikey had a mis-labled reel in their stockroom.

DK is shipping me replacements for Monday, and I have a couple of hundred caps to swap out.

The joys of unlabeled parts!

Charlie

Vishay/Dale CRCW 0603 1% I use are all value labeled. Nothing indicates they are 1% though. Mouser and DigiKey have them.

You damned sure earned your pay.

Good work.

John

is there a four digit number on them?

Good point - yes they do. I went and found the marking document.

Here is a link to the document

I know the code by heart. I've used them for over a decade. :)