I'm trying to buy 6 potentiometers from a local electronic store.

All i have for the project is potentiometer codes , I'm not able to determine if its a log or a linear pot since there is code before the pot value.

POT1 dist 250K A

POT2 low 100K W

POT3 high 100K W

POT4 mid 100K W

POT5 top 10K B

POT6 volume 50k A

which code represents linear or log or other pot?


1 Answer 1


There's a good guide at Beginners' Guide to Potentiometers that includes the following table:

Pot marking guide

Being from an electronics supplier rather than from an old piece of equipment I'd say the A is logarithmic and the B is linear, but it may also vary by region. You'd hope the staff would be able to confirm but it sounds like that's not the case? You could also consider buying online from a place like Digi-Key or Element 14 where they will be properly documented.

This is a bit of a guess but I'd say the W stands for wirewound, they normally have a higher power rating than regular pots and one likely sign is that they'll tend to be slightly larger and more expensive than the others. If that's the case they are normally linear and doing a search at Element 14 all 202 results for a wirewound pot were linear.

But based on e-bay search results it looks like the W suffix is commonly used for pots intended for balance control that have a center detent. Here was the resistance curve shown next to one product:

enter image description here

  • \$\begingroup\$ i had viewed codes on the same website before posting here there is a confusion between A and B. A could be log and linear :( \$\endgroup\$ Jul 14, 2013 at 6:36
  • \$\begingroup\$ @Metalhead1247 other than measuring them I can't think of a 100% sure way to tell. I'd probably either go with a more professional supplier or if you don't mind waiting longer for delivery you can probably find them on e-bay with free / cheap shipping. The local store should know or be able to find out, might be worth talking to a manager if the counter staff didn't know. \$\endgroup\$
    – PeterJ
    Jul 14, 2013 at 6:55
  • \$\begingroup\$ i found one w100k but can you tell me if its a linear or log or close to log? ebay.com/itm/… \$\endgroup\$ Jul 14, 2013 at 7:06
  • \$\begingroup\$ @Metalhead1247, it's got a graph down the page and it doesn't look logarithmic, maybe the W is used for pots like that made for balance control. If I do a search on "100K logarithmic pot" I get quite a few although for most you have to buy a couple. \$\endgroup\$
    – PeterJ
    Jul 14, 2013 at 7:11
  • \$\begingroup\$ i think it is called a commercial log pot? s-curve \$\endgroup\$ Jul 14, 2013 at 8:09

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