Longer lasting Dupont alternatives for cheap LAs, Analog Discovery etc? - Page 1
Forum section: electronics / general

author: Howardlong
author_rank: Super Contributor
timestamp: September 08, 2023, 03:01:29 pm
content: Can someone recommend a source of more hard-wearing alternatives to the 0.1" Dupont receptacles used on cheap LAs and the Analog Discovery?These lose their grip after a handful of insertions.The likes of Keysight, Tek, Rigol & Siglent all use far harder wearing turned-pin style receptacles on the LA probes for their MSOs, but my Google-fu is failing to show up anything that would allow me to put together my own more durable flywire assembly.

author: Someone
author_rank: Super Contributor
timestamp: September 08, 2023, 09:44:11 pm
content: Molex 70058-****https://tools.molex.com/pdm_docs/ps/PS-70058.pdfDual spring box socket. Available preassembled.or the stiffer Molex90119-****71851-****Single pin housing? Nope.

author: thm_w
author_rank: Super Contributor
timestamp: September 08, 2023, 10:18:08 pm
content: https://www.mill-max.com/products/results?q=recs:13531,13551;26841:346&r=recs:13531,13551;26841:13561,13581,356,271,316,306,281,366,321,231,246,241,291,236,266,296,261,171,276,346,341;26881:4366,4361,4331,4321,4371,4326,4346,4316,4376,4381You'll have to figure out the ideal size. They are not cheap. Might be some ali alternatives:https://www.aliexpress.com/item/1005004707554342.htmlOr may not be deep enough, depending on what you are using it for.Usually the recommendation here is to buy an old logic analyzer cable from ebay and use that.

author: Sceptre
author_rank: Regular Contributor
timestamp: September 09, 2023, 04:38:25 am
content: Two options to consider:1. One of the Samtec connector families that use Tiger Eye or Machined contacts:https://www.samtec.com/contact-systems2. TE AMPMODU MOD IV or V Wire Connectors:https://www.te.com/usa-en/products/brands/ampmodu/ampmodu-modiv.html?tab=pgp-storySceptre

author: Someone
author_rank: Super Contributor
timestamp: September 09, 2023, 05:27:27 am
content: Quote from: Sceptre on September 09, 2023, 04:38:25 amLower force than the Molex options, but they have single pin housing and the higher force designs are still 4 sided boxes.

author: tooki
author_rank: Super Contributor
timestamp: September 09, 2023, 06:45:52 pm
content: The gold standard is Amphenol Mini-PV (PV being short for “perpetual virgin” according to the manufacturer). They’re rated for 1000 cycles. They use a separate beryllium copper leaf spring inside the brass body of the female contact. The leaf springs come in three thicknesses, sold as the standard, high-force, and ultra-high-force, so that single and low-pin-count connectors won’t pop off, but high pin count connectors won’t be unreasonably difficult to insert. For single pins, use ultra-high-force, since they won’t come loose by mistake.Single pin housings (65039-036LF) are available, but are stupid expensive ($1.30 each at quantity 50!). However, because Mini-PV is what Chinese DuPont is loosely based on, you can use Chinese DuPont housings (and similar, like Harwin M20) with genuine Mini-PV contacts. The Chinese housings don’t hold on to genuine Mini-PV contacts quite as well as the originals, but you can get 1000 pieces of them for $5 on aliexpress, so if you have to replace a lost one now and then, no big deal.I’ve been remaking all of my “DuPont” test leads with genuine Mini-PV contacts. They cost >10x as much as Chinese DuPont contacts, but last at least 100x as long without loosening. And the reliability makes it well worth it.30cm pre-crimped leads with tin-plated high-force contacts on both ends are available, but sadly no options for gold or ultra-high-force contacts.https://www.amphenol-cs.com/product-series/pv-crimp.htmlhttps://cdn.amphenol-cs.com/media/wysiwyg/files/documentation/customerpresentation/pv_productpresentation.pdfWith that said, Mini-PV is hard to crimp without a good crimp tool.If “only” 300-500 mating cycles is enough, then options like the already mentioned Molex SL, TE AMPMODU, and others (Molex C-Grid, Amphenol Dubox, etc) may have easier contacts to crimp. However, only Mini-PV and AMPMODU offer single-position housings. AMPMODU is slightly easier to crimp than Mini-PV, but is even more expensive!!Instead of individual housings, you can also just heat-shrink over the contact. I’ve done this to make test leads before, using size 22 (e.g. D-sub HD) contacts. Size 22 contacts will mate with standard pin headers, but they tend to not be super tight.If you don’t need the ability to stack multiple single-position connectors next to each other, then JST XH also has a single-position housing, and mates well with individual pins.

author: Howardlong
author_rank: Super Contributor
timestamp: September 13, 2023, 01:14:42 pm
content: Well this has sent me down quite a rabbit hole!After reading this data sheethttps://docs.rs-online.com/e1e0/A700000007538105.pdfI sourced these 22-26 AWG ultra-high spring force female crimp contacts:300 47649-000LF Mini-PV female tin at £0.092 each, reel strips of 100;200 48236-000LF Mini-PV female 30u gold at £0.268 each, loose in bags of 100.Both were ordered from RS.Meanwhile, regarding the crimping tool, I came across these two blog posts:https://www.mattmillman.com/a-new-budget-dupont-crimp-tool-is-bought-to-my-attention/https://www.mattmillman.com/iwiss-sn-025-another-head-scratching-dupont-crimp-tool-lands/I've never had a particularly satisfying relationship with crimping tools, part of it is no doubt the quality of the cheap tools that you find paired with bulk assortments of connectors, and it now seems that the crimping tools I have were never going to work well with Dupont crimp connectors anyway due to the "B" style crimp around the strain relief as well as the wire crimp itself. It seems obvious now, but the strain relief part of the crimp really needs to be a round "O" crimp.So I purchased both the PR-3254 and SN-025 crimping tools to see how I got on: I'm not at a stage where I want to spend four figures on a crimping tool.The crimp results are far neater with both of these, with both the Dupont clone contacts and the kosher tin Mini-PVs I've now sourced. I've yet to try the gold plated contacts.Regarding the looseness and durability of the contacts, it's early days, but so far after multiple insertion cycles it is very clear the tin Mini-PVs are going to last longer.One thing to note is that the tin Mini-PV contacts I have don't fully cover the length of the header contacts they're mating with, leaving a couple of millimeters uncovered. I'm not sure that this is a problem as the fit is so much firmer than the generic Dupont clone contacts I have been using.I never realised there is so much folklore around crimping, and I am sure I have plenty more to learn.

author: PlainName
author_rank: Super Contributor
timestamp: September 17, 2023, 09:27:24 am
content: Quote from: Howardlong on September 13, 2023, 01:14:42 pmThank you! I had a quick look there and, despite the chap having a downer on the Engineer PA-24, realised that was what I was missing and ordered one from Amazon. Came last night, and my very first crimp with it (to demonstrate to the missus why I needed another crimper) resulted in a perfect dupont crimp. Not cheap but Just Works - money well spent so far as I'm concerned

author: tooki
author_rank: Super Contributor
timestamp: November 23, 2023, 08:05:46 am
content: Quote from: Howardlong on September 13, 2023, 01:14:42 pmHow have you fared with the reeled contacts? People generally recommend avoiding reeled Mini-PV because they’re reeled end-to-end (not side-by-side like most contact types), meaning you have to make two accurate cuts per contact to dereel them.Quote from: Howardlong on September 13, 2023, 01:14:42 pmYep, that’s one key element of a proper DuPont crimp: the o-shaped insulation crimp. A B-shape crimp there runs the risk of damaging the insulation (creating a weak spot where the insulation will break) and often a crimp too wide to fit into the housing properly.That website is a great resource I have linked to in the past in other DuPont crimping threads. I am so envious of his collection of crimp tools!!Quote from: Howardlong on September 13, 2023, 01:14:42 pmYeah, you’ll find that the Mini-PV doesn’t get loose in any noticeable way, after the first insertion.Since this thread, I’ve had a chance to try Harwin M20, and despite those contactslookingidentical to generic Chinese DuPont contacts, having the exact same one-piece folded construction, they perform far better than the generic ones.As for the insertion length:1. headers come in various lengths. You may want longer ones.2. Make sure you’re stripping to the correct length. If you strip too much, the overhang sticking out of the conductor crimp can interfere with the pin. The overhang should be around 0.3-1mm. I aim for 0.5mm.And I wouldn’t refer to it as “folklore” — most people don’t realize that crimping is a precision metalworking process. The “rules” are the result of 70-odd years of industry experience and metallurgy research.

author: Howardlong
author_rank: Super Contributor
timestamp: November 28, 2023, 06:42:09 pm
content: Quote from: tooki on November 23, 2023, 08:05:46 amFirstly, apologies for the delay in responding.Yes, reeled contacts are a PITA to split out, but they were (relatively) cheap and locally available in the tinned version ultra high spring force. The gold plated versions were available loose, I'm saving those up for a rainy day.QuoteI've found myself accumulating quite a few myself now! An Engineer PA-24 came my way a few days ago, it's quite small and lightweight as crimping tools go, but needs two actions for each crimp, one for the strain relief and the other for the connection itself. It does have both B and O crimps. I haven't tried it other than a couple of test crimps yet, so the jury's out. Although it needs two actions, it may be less fiddly than trying to align a connector in a dual-action crimp tool.The PA-24 is explicitly designed for: JST PH, NH, XH; Molex 43030, 1560; TE EI; and Amphenol QI/Dupont.The PA-24 O crimpers are 1.4 and 1.8mm. The B crimpers are 1.3, 1.6, 1.9 and 2.2mm.Both TE EI and Dupont use O crimps on the strain relief.QuoteI might get some M20 too. I already got hold of some Molex C-Grid III to try, but they don't seem to have different spring force versions.I tried using a dynamometer to measure any force degradation over repeated cycles, but it'll need an automated jig: doing it by hand is a waste of time, it's not possible to get repeatable results.Regarding my "folklore" comment, that's been my perception, purely down to the apparent lack of canonical information available.I did replace all the single flying lead terminations of one AD2 cable assembly, reusing the existing 1x1 housings, which have thus far shown themselves to be good enough for the job.Regarding getting just the right strip length, I use a Jokari PWS-PLUS 002.PWS-PLUS 001, Mfr# 40024, 26-36 AWG, white thumb pushPWS-PLUS 002, Mfr# 40025, 20-30 AWG, red thumb pushPWS-PLUS 003, Mfr# 40026, 18-28 AWG, blue thumb pushBe aware that Knipex also sell a seemingly identical PWS-PLUS 001 and PWS-PLUS 003. These are not the same! Most importantly, unlike the cheaper Jokari versions, the Knipex versions don't have a guide that goes down to the very short strip length required for these crimp connections. You can still strip with the Knipex versions, but you'll usually find that you have an extra step of trimming after stripping.

author: tooki
author_rank: Super Contributor
timestamp: January 12, 2024, 08:39:52 pm
content: Quote from: Howardlong on November 28, 2023, 06:42:09 pmHave you accumulated any more insight over the past month and change?Quote from: Howardlong on November 28, 2023, 06:42:09 pmFYI, I don’t think that’s a difference between Jokari and Knipex, but rather between older and newer production runs. Earlier Jokari-branded ones also lack the little “nose” that allows for shorter strip lengths. If you do a google image search for the Jokari models, you’ll see pictures of both styles.