Precision trimmers Bourns 3296 vs 3299 - Page 1
Forum section: electronics / testgear

author: Mr Simpleton
author_rank: Unknown
timestamp: September 21, 2015, 08:58:01 am
content: I am currently renovating several PTS1000 signal generators, and they use 50 (fifty) Bourns 3299 trimmers for coarse setting of VCONow the 3299-serise seems to be a lot more expensive and harder to find (at least "my" values) vs the 3296-seriesReading data sheets, it seems it is a drop-in replacement as the only difference seems to be a thinner housing on the 3296. But is there any advantage to keep looking for 3299-potentiometers? Key parameters are noise and keeping performance over time.I rather do this right the first time. Not too fun replacing 50 pots.... on ten units. Leave the math for the readerShould add: The PTS1000 comes with the 3299.. hence the query

author: Psi
author_rank: Super Contributor
timestamp: September 21, 2015, 10:01:43 am
content: Looks identical to me, other than the size as you say.

author: markce
author_rank: Regular Contributor
timestamp: September 21, 2015, 05:11:29 pm
content: 900VAC - 600VAC, 25 turn - 12 turn. Contact resistance variation 1% - 3%The 3299 is more precise the 3296 more enduring (temp, vibration).

author: Mr Simpleton
author_rank: Unknown
timestamp: September 22, 2015, 09:43:11 am
content: @Markce Not sure where you found those specs.... I had a look at:http://www.bourns.com/data/global/pdfs/3296.pdfandhttp://www.bourns.com/data/global/pdfs/3299.pdfThey look pretty identical except for weight and size!I still have to make sure the 3296 is just as good as the 3299, the size is smaller and will fit the PCB, I just have to be sure it will be performing like the 3299 (or better) BTW the 3296 seems to be MIL-listed.Cheers

author: markce
author_rank: Regular Contributor
timestamp: September 22, 2015, 10:48:20 am
content: It's in the left column under 'Electrical Characteristics'.

author: Mr Simpleton
author_rank: Unknown
timestamp: September 22, 2015, 12:16:19 pm
content: Not trying to be a smart alec...I see no electrical difference between these two... both are 25 turns and both shows 900VAC dielectrical strength, if looking at the PDF-links I posted.Are there other specs available that differ the data sheet?

author: markce
author_rank: Regular Contributor
timestamp: September 22, 2015, 04:09:46 pm
content: My 3269 datasheet is for the X style, which is the current product I found. Yours is for the W style, and these apparently also differ electrically. Found the Bourns trimpot catalog on the Farnell site.http://www.farnell.com/datasheets/681515.pdf

author: Mr Simpleton
author_rank: Unknown
timestamp: September 22, 2015, 07:50:54 pm
content: @Markce, are you aware that we discuss 3296 vs 3299 not 3269BTW all my docs are straight from Bourns... not a retailer

author: dacman
author_rank: Frequent Contributor
timestamp: September 22, 2015, 11:01:31 pm
content: I'd use them, but what I'd be concerned with is would the 3296 rock on the board due to it being narrower. A cross for the 3299 used to be the 68 series, although its data sheet presently states that it has 20 electrical turns.

author: markce
author_rank: Regular Contributor
timestamp: September 22, 2015, 11:16:28 pm
content: Sorry, seems to be a typo when searching initially...

author: Mr Simpleton
author_rank: Unknown
timestamp: September 23, 2015, 09:05:22 am
content: Thanks for all information.... not sure it is economical viable to use the 3299 series, it seems to be 2-3 times more expensive and longer lead times. I have to settle for the 3296 and try to secure from vibrations.Cheers