Small PCB trim pot knobs? - Page 1
Forum section: electronics / beginners

author: kalel
author_rank: Frequent Contributor
timestamp: August 16, 2017, 12:10:07 am
content: These things can be quite cheap:and might be accurate enough for some adjustments. In fact, you get them on Chinese buck boost voltage regulators and such. If you're actively adjusting the voltage it could be a bit annoying.Obviously they are designed to be adjusted with a tool, but for convenience, do you know if caps for this exist or could be improvised from something?

author: rdl
author_rank: Super Contributor
timestamp: August 16, 2017, 12:40:41 am
content: I have some Bourns trimmers that have knobs long enough for finger adjustment which are handy for breadboard circuits. I don't know if they have similar multi-turn types though.

author: sleemanj
author_rank: Super Contributor
timestamp: August 16, 2017, 01:07:30 am
content: Yes there are tools you can get, like a shrouded screwdriver in the style of a pen...https://www.google.co.nz/search?safe=off&biw=1680&bih=960&tbm=isch&q=trimmer+adjustment+tool&oq=trimmer+adjustment+tool&gs_l=psy-ab.3..0.3307.4607.0.4760.11.8.0.0.0.0.247.478.2-2.2.0....0...1.1.64.psy-ab..9.2.477...0i5i30k1j0i8i30k1.mtgBdV9SnYs&gws_rd=cr&ei=2pqTWfjaHoGS8wWbmqdo#gws_rd=cr&imgrc=-7oMF4XQE45g8M:Or, find some tube about the right diameter, and a screwdriver, and shroud it yourself :-)

author: sleemanj
author_rank: Super Contributor
timestamp: August 16, 2017, 01:09:54 am
content: You can also get trimpots with knobs, I don't recall seeing them in the tall (3296) type, but in the flat type....https://www.google.co.nz/search?safe=off&biw=1680&bih=960&tbm=isch&sa=1&q=trimpot+&oq=trimpot+&gs_l=psy-ab.3..0i67k1j0j0i67k1j0.13164.14085.0.14489.8.7.0.0.0.0.267.267.2-1.1.0....0...1.1.64.psy-ab..7.1.266.vzZ6To2820k#imgrc=O85he_JxrYYEQM:

author: w2aew
author_rank: Super Contributor
timestamp: August 16, 2017, 12:15:46 pm
content: One of the main reasons that trimpots don't generally come with knobs is because they have a very limited rotational life and should not be used in applications where they'd be operated a lot (like a control).

author: cvanc
author_rank: Frequent Contributor
timestamp: August 16, 2017, 02:16:56 pm
content: Quote from: w2aew on August 16, 2017, 12:15:46 pmYeah, this. Even some of the good ones are rated surprisingly low in this regard. Should be in the datasheet.

author: kalel
author_rank: Frequent Contributor
timestamp: August 16, 2017, 07:31:45 pm
content: Quote from: w2aew on August 16, 2017, 12:15:46 pmYes, that seems quite reasonable. But for some uses, quick breadboard experimentation or other experimentation, and them coming with some stepdowns and stepups makes you want to have a simple way of adjusting without needing to have an adjustment tool or screwdriver with you every time (as an example, I'm using a step down that has one of those for adjustment and a built in voltmeter as an improvised voltage controlled power supply).They are also smaller and significantly cheaper than larger potentiometers designed to be frequently adjusted. For a finished product, it definitely makes sense to use the proper part and consider longevity and definitely other specs too.Maybe a cap could be improvised? Some tube or something, and a little bit of glue. Maybe heatshrink and a bit of heat? The issue with many kinds of glue and trying to glue something to the screw is that it might leak between the screw and plastic and have the undesirable effect of also fixing the position, so that you can't rotate it at all. Trying to apply a small amount of hot melt glue over the screw might work, but I doubt it sticks that great to metal.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 16, 2017, 07:46:16 pm
content: I've done this before: tack some trimmers onto a piece of copper clad, with the surface cut up into islands for each connection as needed. Jumper the pads down to a header. Plug the header into the solderless breadboard.That avoids the trouble of leads that are too short, floopy, or the wrong pitch, and allows you to use SMTs, too.I'm not sure what this has to do with trimmer capacitors...Tim

author: kalel
author_rank: Frequent Contributor
timestamp: August 16, 2017, 07:54:20 pm
content: Quote from: T3sl4co1l on August 16, 2017, 07:46:16 pmBy caps in the title, I meant knobs actually (well plastic or other caps over the trim pot, making them easier or at least possible to rotate using fingers alone). Might be using the wrong term.

author: tautech
author_rank: Super Contributor
timestamp: August 16, 2017, 08:31:08 pm
content: Quote from: kalel on August 16, 2017, 07:54:20 pmIt might read better if you use the word: knob.......I did a doubletake but after reading the OP again I understood you wanted knobs.You can go back and edit the thread title.

author: kalel
author_rank: Frequent Contributor
timestamp: August 16, 2017, 08:34:51 pm
content: Quote from: tautech on August 16, 2017, 08:31:08 pmRight, I've changed the title.

author: Brumby
author_rank: Unknown
timestamp: August 17, 2017, 04:12:29 am
content: Personally, I wouldn't use trimpots on a breadboard setup unless lead length is an issue. I have a panel with 1k and 10k linear pots plus a 100K log pot with some pin header sockets mounted for connection points.

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: August 17, 2017, 06:33:28 am
content: Clippy's Final Destination

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: August 17, 2017, 06:53:25 am
content: These are the best thing...http://uk.rs-online.com/web/p/trimmer-tools/0543434/

author: tggzzz
author_rank: Super Contributor
timestamp: August 17, 2017, 07:46:14 am
content: Quote from: IanMacdonald on August 17, 2017, 06:53:25 amI'm still using one like that I bought ~40 years ago.

author: Raj
author_rank: Frequent Contributor
timestamp: August 17, 2017, 01:37:06 pm
content: You'll have to be creative and stick a small tube to the knob, which later is turned using a bigger knob

author: kalel
author_rank: Frequent Contributor
timestamp: August 17, 2017, 07:08:42 pm
content: Trim tool might even be the best thing in the end, but other creative solutions are great too.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: August 17, 2017, 07:12:16 pm
content: If the goal is a knob for breadboarding why not just use a regular pot? They are pretty cheap from China. They already have a knurled knob of sorts (and can take a real knob). They also fit right into a breadboard vertically.