Bear in mind that all carbon comp resistors are old stock and their values have drifted over the years. If your schematic calls for a 680 Ohm resistor, you might try a slightly lower labeled part in order to get closer to the desired target value. When you buy carbon comp resistors from anyone, ask them for specific MEASURED resistance, not the labeled value. I don't know if you'll get them to do it, but it's worth a try.
High resistance parts tend to drift more than low value parts so you need to be most careful about things like high resistance tube bias resistors.
All the resistances drift upward with time.
MR
High resistance parts tend to drift more than low value parts so you need to be most careful about things like high resistance tube bias resistors.
All the resistances drift upward with time.
MR
Allen-Bradley resistors
As Mark stated I have a large stock of Allen-Bradley Resistors
Some came from him...What values are you looking for.
You can email me at steve.apexjr@prodigy.net
Steve
Apex Jr
www.apexjr.com
As Mark stated I have a large stock of Allen-Bradley Resistors
Some came from him...What values are you looking for.
You can email me at steve.apexjr@prodigy.net
Steve
Apex Jr
www.apexjr.com
Hi Peter,
Thank you for the suggest, I have contact http://www.welbornelabs.com before but all they got is 10% tolerance but I need the 5% tolerance.
Hi Apex Jr and MRehorst,
Do you have any 5% tolerance in stock ? I need some values like
1/2W 5% tolerance 68, 3.3K, 10K, 22K, 27K, 30K, 56K, 100K, 200K, 220K, 250K, 1M, 2.2M.
1W 5% tolerance 18K, 2.7K, 51K, 56K, 100K, 150K.
2W 5% tolerance 12K.
I need 25 or 50 pcs for each values, are they in the original AB package like this ? can you give me a email please ? Thank you very much.
Thank you for the suggest, I have contact http://www.welbornelabs.com before but all they got is 10% tolerance but I need the 5% tolerance.
Hi Apex Jr and MRehorst,
Do you have any 5% tolerance in stock ? I need some values like
1/2W 5% tolerance 68, 3.3K, 10K, 22K, 27K, 30K, 56K, 100K, 200K, 220K, 250K, 1M, 2.2M.
1W 5% tolerance 18K, 2.7K, 51K, 56K, 100K, 150K.
2W 5% tolerance 12K.
I need 25 or 50 pcs for each values, are they in the original AB package like this ? can you give me a email please ? Thank you very much.
Attachments
MRehorst: Carbon comp resistors
the value shifts with time owing to the absorption of water (err, humidity). while picking a lower value and hoping that it will come up to the specified level may sound like a good idea, as the resistor is used and heats up, the moisture is driven out and the value returns to something approximating the original value -- not original to me, I think that I read this in Electronics World or QST, just recently so I am just passing it along.
the value shifts with time owing to the absorption of water (err, humidity). while picking a lower value and hoping that it will come up to the specified level may sound like a good idea, as the resistor is used and heats up, the moisture is driven out and the value returns to something approximating the original value -- not original to me, I think that I read this in Electronics World or QST, just recently so I am just passing it along.
I do a lot of work on antique radios that are filled with carbon comp resistors. My experience has been that the older the resistor, the higher its value drifts. Operation of the circuit doesn't seem to fix the problem- maybe because most resistors are operated so far below their sepc'd power rating that they don't heat up.
MR
MR
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