Female banana question - Page 1
Forum section: electronics / projects

author: berke
author_rank: Frequent Contributor
timestamp: January 16, 2024, 04:25:18 pm
content: I've bought a bunch of female bananas with the hope of making banana extension cords.How does one assemble this thing so that when you try to pull the banana out you can disconnect this instead of pulling the read part over the cable?The solder cup is blind. The purpose of the little hole is unknown to me. There is nothing inside the jacket that matches the hole. What's the secret?

author: chilternview
author_rank: Frequent Contributor
timestamp: January 16, 2024, 04:34:56 pm
content: The small hole is so solder can flow into the connector body, with air escaping thru the hole. Else it would leave a void space - and give a poorer connection.

author: ataradov
author_rank: Super Contributor
timestamp: January 16, 2024, 04:35:30 pm
content: The hole is so that there is a vent for the solder to flow. If the soldering part was entirely blind, once molten solder covers the entire opening, it will trap some air in the connector and will not flow.Usually those things are so tight that pulling out is not a concern. If yours is not tight, it is likely a manufacturing defect. The only way to address this is to use glue to add more friction or something like this.

author: berke
author_rank: Frequent Contributor
timestamp: January 16, 2024, 04:46:22 pm
content: Thanks for your replies. The solder cup is entirely blind, there is absolutely no connection to the hole. Also the grip isn't tight at all.In other words, I just bought a bunch of crap.

author: ataradov
author_rank: Super Contributor
timestamp: January 16, 2024, 04:52:26 pm
content: This is just bad luck, I guess. I have wires made with the same stuff from Aliexpress and they work perfectly. I don't remember if the holes were connected in my case, did not matter for my use.But the hole looks like someone was copying the design without fully understanding it, or they are manufacturing rejects, which is why they are cheap and on Aliexpress.But there are definitely functional versions of them out there, they are not all crap. In my case it was so tight that I would be concerned with disassembling it back. I'm pretty sure it is mostly a one way thing.In your case, since there is a hole, I would put a piece of wire into the hole so that it sticks out a bit. The wire will dig into the plastic and hold it.

author: berke
author_rank: Frequent Contributor
timestamp: January 16, 2024, 05:22:25 pm
content: Quote from: ataradov on January 16, 2024, 04:52:26 pmFor the record It was from Amazon.QuoteGood idea, I might give that a try out of curiosity, but if it's going to be hit and miss like that I guess I'll order those kinds of things from the usual "serious" suppliers next time.

author: jonpaul
author_rank: Super Contributor
timestamp: January 16, 2024, 06:10:04 pm
content: imitation junk from China, like moist of Amazon.We use genuine Pomona banna plugs and all have the correctly machined axial hole and either threaded set screw of solder hole.Jon

author: berke
author_rank: Frequent Contributor
timestamp: January 16, 2024, 07:53:34 pm
content: Quote from: jonpaul on January 16, 2024, 06:10:04 pmI have screw-type male Pomonas as well but they're expensive. I was hoping to find something cheaper for making extensions. The male plugs I got are OK, so it's hit-and-miss.I like Ataradov's manufacturing reject theory. They must have idiots in China too, and when one of them incorrectly configures some machine you get a batch of bad bananas that end up on Amazon.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 16, 2024, 10:12:26 pm
content: Quote from: berke on January 16, 2024, 04:46:22 pmI use similar connectors, they are ok.Possibly, your first try to assemble it was wrong. You have to push it to another end (push it through).

author: berke
author_rank: Frequent Contributor
timestamp: January 17, 2024, 09:28:24 am
content: Quote from: Vovk_Z on January 16, 2024, 10:12:26 pmThere must be significant variation from batch to batch and you probably got the good ones.I've just soldered one. The metal part can only go in from the large end. From there even if I force it to enter the jacket as much as possible it doesn't provide enough grip and when you pull it out from a banana socket you pull out the jacket. Adding a wire in the hole did nothing either. I added some glue, now it's meh.The male ones aren't that great but hold much better and are usable. I also got female-female couplers, so I guess I'll just use those.

author: Gyro
author_rank: Super Contributor
timestamp: January 17, 2024, 12:18:18 pm
content: You might have more success using standard 4mm panel sockets and some adhesive lined, high shrink ratio, heatshrink sleeving. They're easier to source and probably work out cheaper than reputable brand female bananas too.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: January 17, 2024, 12:35:12 pm
content: Shrink heatshrink over the center pin before inserting it into the sleeve for an interference fit. This also provides strain relief on the cable entry - and makes it look pro. I suspect a commercial assembler uses an adhesive or silicone. The little hole is either for a snag/locking bump or, is used in a matching assembly tool.

author: armandine2
author_rank: Frequent Contributor
timestamp: January 17, 2024, 12:41:20 pm
content: Quote from: berke on January 16, 2024, 04:25:18 pmI got some XT150 connectors which have (if I remember correctly) this hole - I assumed it was because if the male/female connection was air tight you couldn't connect them.

author: voltsandjolts
author_rank: Unknown
timestamp: January 17, 2024, 01:16:24 pm
content: For extension, use female-female:https://uk.rs-online.com/web/p/test-connector-adapters/1037508?gb=shttps://www.amazon.co.uk/dp/B09F3LZ8VK

author: tooki
author_rank: Super Contributor
timestamp: January 17, 2024, 07:27:26 pm
content: Quote from: chilternview on January 16, 2024, 04:34:56 pmQuote from: ataradov on January 16, 2024, 04:35:30 pmUmmm, sorry guys, but no. You're confusing two different types of solder terminals. Solder cups of this kind (machined, with the scooped opening) do not have breather holes. I just checked several kinds of connectors with this type of solder cup (banana plugs and sockets, circular military connectors, XLR jacks, etc.) from numerous top manufacturers (Stäubli, Hirschmann, Amphenol, Hirose, Jäger, LEMO, etc) and not a single one has the breather hole. That's because that is the role of the scoop: the base of the hole is not far below the bottom of the scoop.Where you do see the breather hole is in machined contacts that are not scooped, i.e. where the solder well is the full cylinder.Quote from: armandine2 on January 17, 2024, 12:41:20 pmThis is almost certainly what the mating-side hole is for.