Strange symbol for an 3 legget capacitor - please help. - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: May 04, 2022, 02:30:36 am
content: I have found this strange USA standard symbol that looks like a three-legged polarized capacitor. I have searched for it's meaning for almost a week, but I can't simply find it anywhere, have you an idea of what it is?Thanks in advantage. :-)

author: james_s
author_rank: Super Contributor
timestamp: May 04, 2022, 02:52:15 am
content: That looks like it is just what it appears to be, a 3 legged capacitor, it's a fairly large value so the third leg is just for mechanical support but it is electrically tied to one of the other pins.

author: xrunner
author_rank: Super Contributor
timestamp: May 04, 2022, 02:57:49 am
content: Yep ran into them before -https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3544699/#msg3544699

author: free_electron
author_rank: Super Contributor
timestamp: May 04, 2022, 02:58:35 am
content: typically used for capacitors with snap-in pins. they have a extra (or extras) pin for mechanical anchoring, sometimes connected to case (negative)

author: FriedMule
author_rank: Frequent Contributor
timestamp: May 04, 2022, 08:04:33 am
content: So I do "just" have to go into Mouser, digikey or one of the other sites and search for polarizes 3 legs (2 minus) capacitor of 680uF

author: langwadt
author_rank: Super Contributor
timestamp: May 04, 2022, 08:31:35 am
content: Quote from: free_electron on May 04, 2022, 02:58:35 amalso ensure that they can only be put in one way

author: Zero999
author_rank: Super Contributor
timestamp: May 04, 2022, 09:01:23 am
content: Quote from: FriedMule on May 04, 2022, 08:04:33 amWhy are you replacing it? There's no need to, if it's good.If it's faulty it ideally should be replaced with a capacitor with the same, or better electrical characteristics in the same case style. Unfortunately that's not always possible. I've had to bodge capacitors with the wrong case styles into equipment before. If only two pinned components are available, get one with the closet pitch to the board and use silicone or hot melt adhesive for mechanical support. Check the PCB trace joins the two pins which were internally connected in the old capacitor and add a bodge wire, if it doesn't.

author: CaptDon
author_rank: Super Contributor
timestamp: May 04, 2022, 02:20:01 pm
content: Those three legged capacitors were somewhat common years ago in audio power amplifiers for home use in the larger output wattage units, typically in 200wrms per channel units. I also found the capacitors to be secured with RTV (good) and rubberized Ply-o-bond cement (very bad!!!).

author: Capernicus
author_rank: Frequent Contributor
timestamp: May 05, 2022, 11:38:14 pm
content: does connecting the base to the collector doing anything with a transistor, cause then u have a 2 legget transistor.

author: Zero999
author_rank: Super Contributor
timestamp: May 06, 2022, 06:27:24 am
content: Quote from: Capernicus on May 05, 2022, 11:38:14 pmWhat's that got to do with the topic?

author: Whales
author_rank: Super Contributor
timestamp: May 06, 2022, 07:28:56 am
content: Quote from: Zero999 on May 06, 2022, 06:27:24 amThe schematic diagram for the capnot the cap IRL.

author: Simon
author_rank: Unknown
timestamp: May 07, 2022, 07:27:04 am
content: With 2 legs the part can rock and eventually fatigue the pins. With 3 pins it will be locked solid and not move.