-------- In message <CAKn+a3sNg3fE-C8=g-_utwj3ibmeujgvpfapv5yvr7cnn8f...@mail.gmail.com>, Mark Goldberg writes:
>When the pot is used as a voltage divider, theoretically it should have >the same TC throughout, so temperature effects should not affect the divide >ratio or the output. I researched this a bit a couple of years ago in relation to HP5065 C-field tempco The major tempco in pots are mechanical in nature. Plastics have *horrid* tempcos, most in the hundreds of PPM and the best (nylon) barely making it under 20 PPM. Mind you, that is usually measured on relatively large linear extrusions, not small bits of geometrically complicated plastic, like you would use to encapsulate a trimpot. There are trimpots on the market which claim 5PPM ratio stability, but the conditions under which that is measured are not very easy to implement in practice. If you want anything close to 1PPM trimpots, hunt eBay for "ESI dekapot" -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
