What is a shitty connector? - Page 1
Forum section: electronics / beginners

author: John Celo
author_rank: Regular Contributor
timestamp: April 24, 2025, 05:17:06 pm
content: Is it a resistor? Capacitor? Inductor?What changes when going on a scale from 0-to-10, from a very-shitty to a perfect connector?If I add a shitty connector to a multi pcb design, what am I adding exactly?How to model it?What is a flimsy connector that barely works - is it a very thin trace with lots of resistance (ie. voltage drop?)How do I model it?What impact does it have on the rest of the system, etc?How to think about various shitty connectors (ie. duponts, duponts in a breadboard, etc),and how their parameters change over time with wear & tear?Low voltage stuff <9V. 5v,3.3v digital signals and some analog.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 24, 2025, 05:26:48 pm
content: I'm not really sure what you are asking, and it sounds rather like a wind-up, but there is one parameter to pay attention to: how many insertions the connector is rated for. I'm aware of connectors being rated for only 50 insertions, and I wouldn't be surprised if some are rated for even less than that.I'm not sure that makes them "shitty". The specifications aren't secret or hidden, so you know what you are getting. If you don't need more than 50 insertions, that's fine.It's up to the designer to specify components that meet the requirements of his/her design, and that includes connectors, capacitors, switches, semiconductors, and all the others.

author: wraper
author_rank: Unknown
timestamp: April 24, 2025, 05:33:59 pm
content: Insertion spec hardly defines if connector is good or not. For example it may have 10k insertion spec but can be torn off the board with barely any force applied.QuoteGeneralizing is meaningless. Connectors exist for many very different tasks. There is no common denominator to define if they're good beside if they do particular task well.

author: thm_w
author_rank: Super Contributor
timestamp: April 24, 2025, 11:27:40 pm
content: Since this is beginners, I think all OP should be concerned about is contact resistance.Shitty connector = high contact resistance, either initially or over time.So look in the datasheet, find the max contact resistance, and model it that way if needed. Test yourself if you don't trust the manufacturer (use and adjustable power supply and voltmeter to measure voltage drop).

author: Terry Bites
author_rank: Super Contributor
timestamp: April 25, 2025, 12:07:53 pm
content: I think you're asking a question about parasitics and controlled impedances etc.The good connector is the one that's suitable for your application and budget.Voltage and current ratings, inserion cycles and dimensions are a good place to start your selection.You could pay a load for a specialist connector thats entirely unsuitable for your project.A cheap crap one may be just the job.The first rule of component selection is to specify, not buy.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 25, 2025, 07:46:54 pm
content: Quote from: wraper on April 24, 2025, 05:33:59 pmYes, indeed. I was pointing out one parameter to pay attention to. There are many others. 😁I'm struggling to discern what the OP means by "shitty". It's a stupid term because it is subjective and imprecise. You need to decide what characteristics are important to you in a particular application and choose a connector that meets those requirements. That's all there is to it. "Shitty" is just too vague. Shitty is what you get when you buy a connector without thinking hard enough.

author: wraper
author_rank: Unknown
timestamp: April 25, 2025, 10:04:37 pm
content: Quote from: SteveThackery on April 25, 2025, 07:46:54 pmAnd it can be a very good and reliable connector with just 10 insertion spec if it's meant to be used within the device and never disconnected other than for repairs. As I said, it's meaningless in general, with no context.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 26, 2025, 10:34:02 am
content: Quote from: wraper on April 25, 2025, 10:04:37 pmWe seem to be in agreement.I would argue that there is no such thing as a "shitty" connector. There is only a connector which meets the requirements, or a connector that doesn't. The requirements might include physical robustness, operating temperature, soldering temperature, electrical characteristics, insertion count, separation force, and loads of others.The designer is responsible for determining what the requirements are. A shitty connector is one that doesn't meet the requirements. That's all there is to it.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 26, 2025, 01:15:37 pm
content: Sniff at it and you'll know the difference instantly.

author: John Celo
author_rank: Regular Contributor
timestamp: April 26, 2025, 03:28:08 pm
content: Quote from: SteveThackery on April 26, 2025, 10:34:02 amWhat about 2.54mm dupont connectors?I would argue that those are almost universally bad and flimsy.An ideal connector (on a scale from 1 to 10, it would be a 10) would be one which can be modelled by adding "nothing" extra - as it acts virtually as unbroken continuation of a trace.But a shitty connector like a flimsy dupont has to be modelled with things, since it can notably affect the function and performance of the circuit.One of those things would be impedance (if you have a trace with certain impedance) as impedance discontinuity would result in reflections, etc.But what those other things and considerations are..... I don't know, which is why I'm asking.Or sometimes if you connect a LED or a circuit so flimsily, that it lights up at 50% brightness and starts flickering, ie. what's happening in this scenario exactly. (ie. how to model this?)

author: golden_labels
author_rank: Super Contributor
timestamp: April 26, 2025, 05:12:43 pm
content: Quote from: John Celo on April 26, 2025, 03:28:08 pmAs a transient break or as resistance.In DC regime the capacitive part is irrelevant.At voltages used to power LEDs from pin headers, dielectric strength is too high to model it as a spark gap.When the LED doesn’t light up, the resistive part may be as well considered a break.When the LED lights up, it’s an unstable resistor in a suitable range.Quote from: John Celo on April 26, 2025, 03:28:08 pmPin headers aren’t unreliable in any way and certainly aren’t flimsy. 48257 series needs 75 gf to unmate a single pin (175 gf for ultra-high tension), M20 series no less than 20–30 gf a pin. They also offer a good contact, rated for 2–3 amps.If yours are as bad as you described above, maybe you got poor quality ones from some dishonest manufacturer or seller. But this can happen to any connector type. Not only to pin headers.You may also be using a row of pin headers on some product (e.g. single-board computers), that had to be designed to accept both point-to-point wire connections (for experimentation) and entire connectors/boards. Jack of all trades, master of none: you can’t have both and both work great. If the user is to be able to remove an entire 40-pin daughterboard without breaking the device, there is no way a single pin can offer a huge unmating force. But it still shouldn’t be as unreliable as you described.--- edit:also please don’t take this reply as a shaming attempt. We shouldn’t drive hobbyists into needlessly buying more expensive stuff. And sometimes one buys what one can afford. But facts are facts regardless of individual person’s situation, and the comment above discusses what pin headers can offer.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 26, 2025, 07:20:49 pm
content: Quote from: John Celo on April 26, 2025, 03:28:08 pmAnd I would argue that they have met all of my requirements dozens of times, so for me they haven't been shitty.You don't seem to have understood my argument, which is that we should remove all subjective and pejorative terminology and for any particular application simply list all the characteristics you want, and then select a connector that meets them. If that includes a degree of robustness that a 2.54mm DuPont can't meet, then choose something that can. If the electrical characteristics are important, choose a connector that meets them.It's really very simple and eliminates all this ridiculous and frankly childish "shitty" nonsense.Are you a troll?

author: John Celo
author_rank: Regular Contributor
timestamp: April 26, 2025, 08:37:38 pm
content: Quote from: SteveThackery on April 26, 2025, 07:20:49 pmLast time I checked it's childish to read into it and get emotional and offended when flimsy 2.54mm dupont connectors (ones that become very loose after few insertions) and patch wires that barely hold together get called "shitty".My bad, who would have thought that the ones that come in all sorts of beginner kits and make - dare I say, shitty connections after just few insertions - turns out actually meet some sort of requirements (despite me never seeing them in any commercial product).Are you a troll?I always thought connectors aren't made equal, and many of which are just kind of "shitty" and are used despite that mostly due to cost.And since various "shitty" connectors might be unavoidable reality of cost optimized consumer electronics, it would be good idea to figure out how to model and reason about them, to work around their less than ideal qualities.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 27, 2025, 12:13:36 pm
content: Quote from: John Celo on April 26, 2025, 08:37:38 pmEh? You are joking! I am absolutely not, even remotely, emotional about this subject! 😂I've simply tried, and tried again, to point out that value judgements like "shitty" have no useful role in the world of electronics. Electronic engineering is logical, scientific and rational. It is in that light that components are specified and procured.I asked if you were a troll because, despite the various replies, you evidently either haven't read them, or haven't taken on board the points they make. You simply keep repeating your opening position.Quote from: John Celo on April 26, 2025, 08:37:38 pmThat is a great example of what I've just been saying. Did you read my comment about connectors having a specified number of insertions? There is nothing "shitty" about a connector being specified for only ten insertions (say) and getting loose after that. Ten is more than enough for many roles. In other roles, 50 or 1000 insertions might be required, in which case you would choose a different connector.Quote from: John Celo on April 26, 2025, 08:37:38 pmCost is a totally valid parameter for selecting a connector. You must have realised by now that sometimes desired parameters clash: a waterproof connector costs more than a non-waterproof one, all else being equal. But this changes nothing: if waterproofness (say) is important, but the designer chooses to forego that in order to save costs, then the product will probably fail due to the connector letting water in. The non-waterproof connector isn't "shitty", it is simply specified wrongly.If you are having trouble with the connectors you are using, then you are either using them outside their specification, or the product manufacturer specified the wrong connectors. Neither possibility requires any shit.Anyway, I'm repeating myself to the extent that it feels like beating my head against a brick wall. I think you probably are trolling, so at this point I will step back. When you respond, I suggest you do so in a slightly more constructive manner. That way you will get much more help.

author: John Celo
author_rank: Regular Contributor
timestamp: April 27, 2025, 06:16:46 pm
content: Quote from: SteveThackery on April 27, 2025, 12:13:36 pmIf instead of beating your head against the wall, you stopped for a second, reread what was asked in original OP and tried to understand what I'm actually asking. Instead of presuming the question isn't asked in good faith or getting all sensitive and bothered about terms used.You'd quickly find out the question is explicitly an engineering one and you're shitting it up by getting all emotional about it.Fortunately, there were people before you who did understand the question (ie. parasitics, impedances and how these change over time as the connectors become more loose and make bad contacts and how that impacts their characteristics and rest of the circuit, and how to model these parameters)...

author: Gyro
author_rank: Super Contributor
timestamp: April 27, 2025, 07:58:42 pm
content: Your question has no engineering validity. It can't unless you quantify your "shitty" definition in real terms.Quote from: John Celo on April 24, 2025, 05:17:06 pmYou need to define your signals much more clearly than that. Whether stray inductance and capacitance are relevant is dependent on signal rise and fall time, source impedance and load impedance. You will also need to characterize your PCB traces and any associated wiring (assuming that the connectors are not directly board-board) as they will be at least as relevant in a fast signal situation. If you are worried about crosstalk, that is down to your pin allocation. If your signals are slow with undefined rise and fall times and impedances then connector inductance and capacitance are irrelevant, resistance is the only factor in play.Quote0-10 on a shitty scale is meaningless in engineering terms.Being charitable, 0 on your scale will be clearly defined in the manufacturer's datasheet, in terms of initial contact resistance, and for a controlled impedance connector, other parameters too. It will hopefully have contact resistance at rated life and vibration specs for non contact interruption.I'll take a guess that 10 on your shitty scale is an open circuit, but it is probably more compex than that. ie. a random variation in resistance from initial contact resistance spec to it's insulation resistance [Edit: Over time from ns to the lifetime of the assembly]. It will be dependent on many factorsincludingthe mechanical characteristics of your assembly - stresses imposed on the connector, resonant modes, exposure to shock and vibration etc. Number of insertion cycles that the connector has been subject to, relative to its rated life.As for 1 to 9, I have no idea, and I'm sure you don't either.QuoteIf you are referring to 10 on your shitty scale, how do you model random. As far as I'm aware, you can't.As has already been pointed out, you specify your connectors according to the design requirements, including electrical characteristics that I have mentioned (eg. controlled impedance), lifetime required number of mating cycles (which for many volume production assemblies will be 1) etc.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 27, 2025, 08:10:44 pm
content: You miss the point. I wasn't trying to answer your question. I was explaining why the premise of your question is wrong.It looks to me like others are sending you the same message:"Generalizing is meaningless. Connectors exist for many very different tasks.There is no common denominator to define if they're good beside if they do particular task well." - @wraper"The good connector is theone that's suitable for your application and budget." - @Terry Bites"The first rule of component selection is tospecify, not buy." - @Terry BitesENOUGH!Let's put all that aside and return to the question. Why exactly do you want to model defective connectors? It's just that most actual defects manifest as intermittent or permanent high resistance, electrical noise, intermittent or permanent disconnection. Theoretically, under just the right conditions, a faulty connector might rectify very small signals. Finally, if a connector's water protection fails, you might see low resistance between the pins/sockets, or to nearby metalwork (plus noise, etc, as above). Intermittent faults often manifest when the connector is subject to motion. Those are the main failure modes.There is also the issue ofunsuitable(not defective) connectors. Unsuitable includes: inadequate current rating, too much contact resistance, too much inter-pin/socket capacitance, inadequate voltage rating, not enough insertions count, not waterproof, too expensive, too much or not enough insertion or separation force, not self-locking, not UV resistant, not complying with legal standards..... I bet you can think of others.Most of that second group you wouldn't really want to model, except possibly the inter-pin capacitance, and that should be pretty straightforward. As for the first group, I would think it is a bit tricky modelling intermittent faults, but high leakage, high resistance and noise injection should be straightforward.I'm intrigued by what is behind your question - please tell us more! 😁EDIT: It occurs to me to mention that there are other types of modelling related to connectors which are in the realm of reliability engineering. That is more about the impact of connector failures on the system as a whole, and what steps (if any) can be made to mitigate such failures. There is more to be said, but it might be off-topic for you.

author: John Celo
author_rank: Regular Contributor
timestamp: April 27, 2025, 09:51:52 pm
content: Quote from: Gyro on April 27, 2025, 07:58:42 pmThe whole point of the question is to learn measurable qualities involved that define connectors of various kinds such that I don't have to use the term "shitty" anymore - and can have the "shittiness" defined by exact measurable quantities instead.Althought the point really isn't to define "shitiness" per se rather than to understand variables that define large and notable deviations from the "ideal" such that they can be modelled, accounted for and dealt with appropriately in the design.The "Ideal" connector being a connector that... doesn't exist (and can't be measured - because it's "barely" even there). Ie. continuation of unbroken trace that doesn't require any additional modelling other than that you'd already do for treating a trace as a transmission line.I appreciate you making the effort to interpret what I'm saying charitably though.

author: tggzzz
author_rank: Super Contributor
timestamp: April 27, 2025, 10:06:57 pm
content: Read textbooks, datasheets, application notes.Look for claims that a connector is particularly good in some respect, and infer others aren't.Look for connector standards, and understand what the standard specifies,and why.Bandwidth, crosstalk, current, voltage, temperature, corrosion resistance, shock resistance, vibration resistance, price, number of matings etc.Yes, that could be a lot of work, too much for casual answers on a forum.

author: incf
author_rank: Frequent Contributor
timestamp: April 27, 2025, 10:31:16 pm
content: Good connector systems typically have piles (50 pages or more) of supporting documentation, specs, tests, usage notes, etc. to 'prove' they are suitable for a particular purpose. (which may or may not be applicable for your product)Read and understand all of the work that goes into certain types of connectors/application. Also appreciate that other types of connectors might not have had the same level of rigor applied during design, testing, and manufacturing - often because it is not needed for certain tasks.https://www.molex.com/en-us/products/part-detail/26013115

author: golden_labels
author_rank: Super Contributor
timestamp: April 28, 2025, 12:28:52 am
content: JohnCelo:calling you “a troll” is an expression of how a person feels, when they try helping you, but you blatantly disregarding that help. Moreso, you completely ignoredthe post giving you a straight answer, at the same time replying in the thread and focusing on unproductive quarrel. Pause for a moment, look at the thread, consider how you look like. Because with each post your’re sinking deeper.

author: SteveThackery
author_rank: Super Contributor
timestamp: April 28, 2025, 10:16:31 am
content: Quote from: golden_labels on April 28, 2025, 12:28:52 amI think I'm also responsible. I tried to explain why there is no such thing as a "shitty" connector because the term is subjective and has no engineering meaning (therefore the premise of his question is wrong), and the OP should see the subject in terms of "suitable" and "unsuitable".When he refused to engage with the point I was making, I should have seen the signs and left him to it. Silly me.FWIW, this whole thing still smells a bit off. The OP clearly knows whathemeans by "shitty", so surely it must be obvious to him what needs modelling. Your earlier reply was excellent, although only the four bullet points directly address his question and I think he could have worked those out for himself. In the rest of your post you explain what others have said: it's the requirements that matter, and a connector (2.54mm DuPont in this case) either meets them or it doesn't. No shit required.Also, what does he mean by "model"? Will SPICE model an intermittent noisy connector due to low contact pressure? I don't get it, and the OP has refused to engage with the technical aspects of the discussion.Anyway, I'm sorry for continuing the argument for too long. I should have realised that I was flogging a dead horse and left it alone.

author: BFX
author_rank: Frequent Contributor
timestamp: April 28, 2025, 01:05:25 pm
content: There is no "shitty" connector there is only "shitty" designer.

author: NE666
author_rank: Frequent Contributor
timestamp: April 28, 2025, 01:35:48 pm
content: Quote from: BFX on April 28, 2025, 01:05:25 pm