Suitable alternative resistor


 
K

Keith J

New member
First off, big thanks to Bryan for the awesome (and accessible) work he's done. Second, I'm not a competent electrical engineer in the slightest. I took physics in high school a decade ago and then went in a completely different direction with my educational career. That being said, I've got a good soldering iron and with a box of the right parts and instructions, I can make a thing.

With all that out of the way, my question. I started ordering the sundry bits for this project last night and everything went well, except that Mouser had the Metal Film Resistors - Through Hole 390ohm 1% 100PPM on backorder with a projected 9-week wait time. That eats up a lot of prime BBQ time and would leave me with a box of parts and sadness for longer than I'd like.

So, I'm trying to find a suitable alternative component. I've found lots of similar components but all have one or two properties that are out of spec. Again, knowing little about the actual theory behind the parts, I can't tell what's critical (except, I'm assuming 390 ohms and through-hole are musts), and what's not. Anyone with the skinny on a suitable replacement that is in-stock somewhere will have a computer-climate-controlled brisket named after them (until it's eaten, of course :p ).

Thanks in advance.
 
Hey, you should be able to source those at radio shack locally. And yes, 390 ohm thru-hole are a must but you can probably get a different tolerance and/or wattage. You can try this one.
 
Yeah any generic part should be OK, I think I just selected those so they'd all be the same brand as the parts that needed to be tight tolerance.

Carbon film vs Metal film: OK
10%, 5%, 1%, 0.1% tolerance: OK
1/2W, 1/4W, 1/8W: OK
 
Fantastic! Thanks for the responses guys. Looks like I might get this thing built and tested before the 4th :wsm:
 
Bryan Mayland said:
Yeah any generic part should be OK, I think I just selected those so they'd all be the same brand as the parts that needed to be tight tolerance.

Carbon film vs Metal film: OK
10%, 5%, 1%, 0.1% tolerance: OK
1/2W, 1/4W, 1/8W: OK
Click to expand...

Any generic part? Does that mean all the resistors. Why I'm asking is that I was going to order some resistors for my maverick et-733 probes but as the shipping here is quite expensive I was thinking of buying some extra resistors for a second kit that I could play around with. Would it be ok to just use carbon film 0.25W 5% for all resistors?
 
Sure, if all you can get is 5%, which is quite a spread at 10K. No chance of getting 1% or 0.1% resistors?
 
Actually for the 10k resistors you have an ace up your sleeve, which is that you directly enter their resistance into the WebUI. Once you've got them installed, just don't put anything into the jack (so they will be out of circuit effectively) and measure the resistance across them. Enter that value for each into the webui in the "resistance" box. You'll have even more precise readings than anyone else because they will effectively be 0.0% tolerance at that point.

Of course they may drift slightly due to temperature but we don't compensate for any resistor so we're all in the same boat for that.

I specify 1% to save everyone the step of having to measure their own resistors, but they could be off by 30% and you'd still be ok!
 
I could always get some different resistors but I found resisistor kits with different Ohm values but they all had the same tolerance and wattage.

Bryan Mayland said:
Actually for the 10k resistors you have an ace up your sleeve, which is that you directly enter their resistance into the WebUI. Once you've got them installed, just don't put anything into the jack (so they will be out of circuit effectively) and measure the resistance across them. Enter that value for each into the webui in the "resistance" box. You'll have even more precise readings than anyone else because they will effectively be 0.0% tolerance at that point.

Of course they may drift slightly due to temperature but we don't compensate for any resistor so we're all in the same boat for that.

I specify 1% to save everyone the step of having to measure their own resistors, but they could be off by 30% and you'd still be ok!
Click to expand...

Great!

Thanks for the answers.
 
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