Contents

Introduction

As someone who builds a lot of electrical things, one of the perhaps most unexciting yet fundamental subject areas is connectors. The range of connectors available and in-use today is trully astonishing. Big sellers like Digi-key/Farnell/Mouser literally have tens of thousands of product lines in their connectors category!

With so many different types of connectors available, it’s often difficult to know what to buy, especially when you’re buying for general use or “personal stock”. On this page I’ll cover some of the most common connectors in use today, and detail crimping/tooling considerations. Towards the end of the article I also cover some types of connector which used to be popular, but aren’t so much anymore.

Every connector system ever conceived has its own official crimp tool, in most cases the cost of these is over and above what any hobbyist could and would want to pay for a crimp tool.

I personally own many of the official tools but for cost reasons don’t necessarily recommend them. Throughout this page I’ll demonstrate the use of two inexpensive generic crimping tools: the Engineer PA-09 and PA-21, and compare them against the genuine parts.

For the past 5 years this page has been focused on comparisons with the above tools. Note that I do not recommend buying these. They are expensive, poorly machined to the extent that contacts get stuck in the jaw, and the scissor type action makes it nearly impossible to get sufficient force on the wire crimp.

I am currently in the process of reviewing other inexpensive tools. In the mean time, the below video is a good look at some of them:

What differences can I expect using original tools versus generic tools?

These are four main differences:

Single action: All original tools allow insertion of the contact and crimping in one go. Generic tools will often require the insulation and wire crimp to be performed as separate actions

Correct crimping force: When using generic tools, it can often be difficult to get sufficient crimping force, especially when crimping thin / small gauge wire into terminals. It is also equally easy to over crimp terminals, damaging the wire in the process.

Locator: All original tools have a ‘locator’ which holds the terminal in place during crimping, this means that your crimps are perfect every time. Using generic tools, it can be frustrating trying to line the terminal up correctly.

Insulation crimp accuracy: Original tools are designed to not piece the insulation, whereas generic tools do most of the time. This means that terminations subject to continual mechanical stress are going to last a lot longer.

Cost: Original tools are all extremely expensive. Unless like me you’re happy to prowl eBay looking for deals on second hand original tools, expect to be paying hundreds to over a thousand dollars (USD) / £ (GBP) for an original tool, only to have it work on a single connector family! To rub additional salt into your wounded wallet, it’s not uncommon to find that the connector manufacturer has a different tool for every single wire size, each costing $500+

What’s wrong with just soldering terminals?

Before I even get started, let’s cover this one briefly with a simple diagram:

When crimped properly, the strands remain individual even upon entering the insulation crimp, making the chances of strands breaking low.

When soldering, there is a very high chance that the solder will wick up the wire, beyond the insulation crimp, making it very vulnerable to mechanical damage. In this situation, it only takes a small amount of movement to start snapping the strands at the invisible weak point.

Soldering doesn’t have any disadvantage in electrical terms, only mechanical. That make this method non-viable for production use; except under very controlled conditions with connectors that are designed for soldering. This having been said, I would recommend soldering in scenarios where connectors are carrying significant current, and the manufacturer tool is unavailable (see below).

Load testing terminals crimped with off-brand tools

If you aren’t using manufacturer original tools, but your connectors are carrying significant current: Load test them before you leave them in-situ. If you think it’s going to carry 10 amps continuously, then test it as such. Manufacturer current ratings mean absolutely nothing if you haven’t crimped them with their tools. While many cheap tools may make nice looking crimps, correct force on the wire part is not a given. Even if it tests good, you may still have future problems because moisture is going to leak in over time, react with the different metals in use, and you’re going to end up with a meltdown. Because of this, you will also need to inspect your terminals regularly. I was personally caught out by this a number of years ago on some Molex KK.156 connectors, crimped by a generic tool I bought off eBay. They worked just fine, then failed spectacularly after 3 years.

Failing this, just solder them. This is never an issue with manufacturer original tools as the terminal and wire are squashed into a solid mass with no possibility of any moisture ingress.

Gold plated vs Tin plated terminals

Back when I first started using crimp terminals, almost everything I built made use of cheap (often off-brand) Tin plated terminals. Why waste money on gold plated terminals when no-brand Tin plated terminals work just fine?

Fast forward a few years, and I find that some of that equipment I built 3-5 years ago begins to malfunction. This turns out to be those knock-off Tin terminals I used, which have gradually corroded over the years. It doesn’t seem to be an issue so much for connectors carrying power, but I have had failure after failure in signal carrying connectors.

Attempts to save a few quid back then have now resulted in hours of profanities as all of those connectors have had to be re-crimped with gold terminals, because as I now know, when it comes to own-built gizmos which are a part of your day-to-day life, those crappy eBay connectors you bought 4 years ago are going to fail at the most inconvenient time.

If you are not on a tight budget, and building something that has to be reliable, and last – go straight for manufacturer original gold plated terminals. If buying Molex: 0.38µm “Selective” plated terminals are good enough (unless your creation is a life support system, or going to the moon).

Alternatively, if you don’t want to stump up for gold plated terminals – Tin plated terminals from known brands i.e. Molex / Amphenol / JST will last a lot longer than no-brand terminals.

Brass vs Phosphor bronze terminals

Phosphor bronze is also a type of brass (copper mixed with other stuff) however with different properties. Phosphor bronze terminals are generally regarded as superior as they are harder and retain their tension for significantly longer. Smaller brass terminals may need to be re-tensioned after 5-10 mating cycles. If a terminals material is not specified (i.e. it’s a cheap no-brand type) assume it’s brass.

There are other exotic materials used in terminals i.e. beryllium alloy however these tend to only be found in very expensive terminals (for example genuine Mini-PV).

Mini-PV – (Amphenol – formerly FCI, formerly Berg, formerly DuPont Connector Systems)

These are often referred to as “DuPont” connectors. This is not an ideal name for two reasons: DuPont Connector Systems made many families of connectors, and the ones we commonly refer to as such aren’t quite the same as DuPont’s original “Mini-PV” design.

So what should we call these connectors then? Quite frankly – I have no idea.

The top three housings are clones, and the larger is an original. Can you spot the difference? Stuffed if I could have at first!

The headers Mini-PV mate with are sold under the trademark “Bergstik”. Top left and bottom right are original Amphenol parts, not that it really matters for headers, as they’re both of identical 2.54mm spacing.

Original Mini-PV connectors and terminals are rarely seen, perhaps not surprisingly (not least due to cost considerations), despite looking almost identical to common clones, Mini-PV terminals/housings and clone terminals/housings are surprisingly not interchangeable.

It’s barely visible, but you can make out the differences in the image above. The Mini-PV housing has just a tad less room for the contact, stopping you in your tracks when you go trying to stuff clone terminals into them. Inserting original terminals into clone housings doesn’t work too well either – they’re too loose and tend to fall out.

Original terminals (left) are ever so slightly slimmer. This is somewhat of a bummer when you consider that the range of original housings is more extensive, better quality and more reliably obtainable than clones, and that original Mini-PV terminals (especially gold-plated) are eyebrow-raisingly expensive.

That having been said, there is one very significant difference between clone and original terminals: Original terminals are a much better design and retain their tension for hundreds to even thousands of mating cycles.

I find that clones have to be re-tensioned every 5-10 mating cycles (they become quite unreliable if used more than that) which is a right pain in the backside for prototype use. Essentially – clone connectors are for “plug it in and leave it alone” use cases only.

I’ve now reached the point where I’m going to throw out all of the breadboard jump leads I’ve made with clone terminals and replace them with new leads using original parts. It’s a darn shame that the 1×1 housing for original terminals (65039-036LF) – the exact one you’d want for prototype use – is ridiculously expensive.

In terms of Amphenol’s tools – I’m aware of three official parts:

HT-95 (HT-0095): The current Mini-PV crimp tool. A large, expensive, clumsy tool, which despite being heavy as heck and not particularly easy to use, does do the best job of crimping.

A reader notes that HT-100 (HT-0100) is also suitable for crimping these terminals. I have not verified this myself.

The price of this tool brand new seems to fluctuate between high and extremely high. I have seen it sold for as little as $800, as high as $1600. It was $1100 last time I looked (Digi-Key).

My one is an old DuPont branded tool, identical to the current one, which I paid one hell of a lot less for second hand.

I also removed the ratchet mechanism (and added a piece of string to hold it shut) as it has no manual release, meaning if you get a contact stuck in the wrong way during crimping, the inevitable result is a busted crimp jaw, which does not cost under £100 to fix (yes, it happened to me).

There are two other tools for this series:

HT-208A: Historic tool for crimping 22-26AWG wire

HT-213A: Historic tool for crimping 28-32AWG wire

If setup properly, They’re much nicer to use than HT-95, but fairly rare. Can only be had second hand these days. If attempting to purchase one of these tools – I would recommend focusing your search on an HT-213A as AWG 28-32 is a more useful wire size for this type of connector.

All three tools crimp both original and clone terminals just fine.

Crimping with unofficial tools

From left to right: Generic terminal crimped with PA-09, Generic terminal crimped with HT-95, Original terminal crimped with HT-95

Mini-PV is the one and only light terminal family I’ve encountered which generic tools such as PA-09 suck at crimping. As can be clearly seen above, the insulation crimp is a mess, often these won’t even fit into the housing.

The problem is apparent when we examine the upper half of the crimp jaw. The original tool is clearly cylindrical, whereas the generic is split, with the intention of curling each side around and back down into the wire again, which is most certainly not what we want for this type of terminal.

I recently accidentally came across a very inexpensive tool – YTH-202B which has a cylindrical jaw on on its AWG 26-28 position (!!!), which happens to do near perfect Mini-PV crimps (on the insulation part at least).

One downside is that is has no suitable jaw for the wire crimp, so you still need both the YTH-202B and Engineer PA-09 (or something like it) to do crimps like the one below. The other downside is that it only covers AWG26-28 wires. AWG 24 is a little fat for this tool. Not that this matters, as AWG 24 is generally a little large for these connectors anyway.

If you want a single tool, the Hozan P-707 likely does both insulation and wire crimps, but I do not own it nor have I tested it.

Male terminals

Above is a couple of types of eBay purchased male terminals. The DuPont designed tool I mention here do not take male terminals out of the box, so either they have to be modified or generic tools must be used.

I’ve modified my HT-2xx tools to crimp these, by adding a 1×1 housing to the locator mechanism:

PH – (JST – Japan Solderless Terminal)

This 2.0mm pitch connector is very commonly seen in consumer electronics. They’re dirt cheap, reasonably compact but not so great in terms of robustness.

The official tool is WC-240.

The WC-240 is nice to use, but there’s not a lot to set it apart from generic tools for occasional use. I personally crimp a large amount of PH, hence the investment in the official tool.

Left: Terminal crimped with PA-09. Right: Terminal crimped with Original tool (WC-240).

XH – (JST – Japan Solderless Terminal)

This is a slightly larger edition of the PH connector, except with 2.5mm pitch, and slightly larger terminals. Once again, mostly found in low cost consumer electronics.

I don’t use these very much but one advantage of them is height. The mated assembly is considerably slimmer than any other type of connector I use. It’s a shame the pitch isn’t 2.54mm – I would use them a lot more otherwise. That said, you can usually jam 2 or 3 (maybe even 4) position headers onto strip board if needed.

The official tool is WC-110

I wasn’t going to bother covering the differences between this tool and generic tools, because they looked so similar, but lately I’ve been noticing something –

When we look at the crimps top down from the rear, we see that the original tool has beautifully curled the insulation crimp ends around, pressing neatly on the insulation without piercing it. This explains one of my biggest gripes with these connectors, which went away when I started using the original tool: The insulation keeps tearing off.

This problem is particularly acute with this type of connector because the transition from wire to terminal is at flush with the top of the housing, so if there’s already a tear created by the crimping process – it only takes a few movements back and forward to create the above mess.

Picoblade (Molex)

Very small (1.25mm) pitch connectors commonly found on laptop and VGA card fans.

KK 254 / KK .100 (Molex)

This type of connector is produced by a very large number of manufacturers. For the most part, headers and housings mate and latch fairly well across brands.

Sub series:

KK 6471 – Housings

KK 6410 – Headers

KK 7395 – Headers (Right angle)

08-50-0113 – Terminal (Tin plated)

08-50-0114 – Terminal (Tin plated, Pack of 100)

The application most people have likely seen it in is as the connector for PC 2, 3, and 4 wire fans.

For the most part I don’t buy original Molex parts, with the exception of the oddball 47054-1000 housing and 47053-1000 header – both have the specially tweaked polarisation for 4-wire fans (pictured below).

63811-8200: Official crimp tool

Left: Terminal crimped with PA-09, Right: Terminal crimped with Original molex tool.

I don’t think the result of the PA-09 is unacceptable, but it requires a lot of force to get sufficient crimp on the wire part, subsequently leaving you prone to then over crimping the insulation part, in many cases severing the wire off completely, and having to start again!

The official tool is a lot easier and faster to use! it also does not end up piercing the insulation after crimping. If you crimp a lot of these like I do, I suggest waiting around on eBay for one to come up cheap, it’s worth it.

Unofficial male connectors

Unfortunately there is no standard male connector in the KK 100 family, but this hasn’t stopped a slew of unofficial connectors from being produced.

Above is a variety of Chinese manufactured connectors I’ve purchased off eBay and Alibaba which are designed to mate with KK 100 female connectors. They are only found in 2, 3 and 4 positions, because, these are the variants used for PC fans.

The quality of these is not comparable to that of the mating connectors, but perhaps this is not so surprising, given the intended market of these connectors.

AMPMODU MTE (TE Connectivity), SL (Molex)

A common 0.1″ (2.54mm) pitch connector which is similar in appearance to Mini-PV, even mates with Mini-PV but is quite different in design, in that the retention mechanism is part of the terminal, where as with Mini-PV it is part of the housing. Not surprisingly, terminals and housings are not interchangeable. It is manufactured by both TE and Molex with some minor differences.

The most likely place you’ve seen them before is in PCs on the cable that traditionally connected the CD-ROM drive audio signal to the sound card.

If I were to start over, I would probably use these connectors in place of several others I commonly use, this is because it is truly a “do-it-all” connector family.

With 2.54mm pitch, they’re good for breadboard, strip board and anything else like it, they have a reliable and practical wire-to-wire male connector, they’re polarised, latching and terminal retention is very good i.e. in male housings they don’t flop around risking bending on mating. There’s even panel mounting options!

They’re not particularly cheap, but if not on a budget, well worth considering.

From Molex there are two crimp tools for SL:

63825-8800: AWG 24, AWG 26, AWG 28, AWG 30

63811-8700: AWG 22, AWG 32, AWG 34, AWG 36

64016-0201: Budget crimp tool (Works with SL, but not designed specifically for it)

From TE:

91531-1: $850 !!!

For all but specialty uses, 63811-8700 is effectively useless. SL is not a particularly good system for AWG 22, or AWG 30+ wires.

Unlike Mini-PV which almost no generic tools can crimp properly – SL Terminals crimp pretty well with off-brand tools.

As we can see from the picture above we have a familiar problem of not being able to apply the same kind of force. The original tool is designed in such a way that a large amount of pressure can be applied to a small area, but on the Engineer tool this just isn’t possible short of jamming the jaw into a vice every time, which’d be a little time consuming.

The lack of crimping force isn’t going to be an issue for the most part. It just means that it’s conceivably possible that the wire could be yanked out of the terminal, and if pushing these terminals to the absolute maximum current rating (which you shouldn’t be), there’s potential of meltdown – assuming the contact doesn’t give first.

CGrid III (Molex)

Very similar to the SL series mentioned above, except comes in a two row configurations. Commonly found in name brand computer equipment, i.e. Dell / HP etc on front panel to motherboard connections. Mini-PV knock-offs are too poorer quality for these companies, and genuine Mini-PV is too expensive, so these fill the gap.

Of course, they couldn’t have possibly have just used the same type of terminal as SL. Instead the terminals are ever so slightly different. Yup – you guessed it. There’s a different tool for them! That’s another $350 please. I generally crimp them by folding down the locator in the SL tool, and lining up the terminals by hand. As with SL there would be no issue crimping them with other branded tools.

KK 396 / KK .156 (Molex)

Effectively a jumbo version of the KK .100 connector, this is another very common wire-to-board connector of which compatible connectors are made by a large number of manufacturers. Pitch spacing is 0.156″ (3.96mm). The most likely place you will encounter them is inside of switching power supplies, almost certainly on the primary side, and possibly on the secondary side too.

There are two varieties of terminal: basic and “trifurcon” – a special variant which contacts the pin on three surfaces for increased current carrying capability.

63811-7500: Official crimp tool

Left: Crimped by Molex 63811-7500

Centre: Crimped by Generic tool (HT-225D)

Right: Crimped by Engineer PA-21

As expected, the original tool is effortless to use and gets absolutely perfect results.

Due to their larger size and awkward shape, they do not crimp easily with the Engineer tools (although it is definitely possible). I have a cheap tool (Model # HT-225D) which does a pretty good job of these, albeit not quite applying enough force to the wire crimp.

Update: Don’t use HT-225D for crimping these terminals. I recently had a few go up in smoke under heavy load, and it was because of insufficient force on the wire crimp. I went back to check a few others too and found those were also in a dangerous melted state.

Mini-Fit Jr (Molex)

Used for 20 and 24-pin ATX power supply connectors, and for the 4, 6 and 8 pin +12V connections found in modern PCs.

There are two official crimp tools for this family:

64016-0200: (Budget) 16 to 28 Gauge

63819-0900: (Premium) 16 to 24 Gauge

The extraction tool

Sold separately (11-03-0044). If you’ve ever found yourself trying to remove already inserted contacts, you’ll appreciate one. Instead of potentially hours of uttering profanities attempting to extract contacts with sewing needles, the contacts will pop straight out with one of these.

Crimping with unofficial tools

Crimped Mini-Fit Jr terminals

Left is a terminal crimped with the Engineer PA-21. Pretty good really, about the same result as the budget Molex tool would produce, albeit with less ability to apply the minimum recommended crimping force.

On the right is a terminal crimped with the original tool, the big difference is that the insulation crimp is cleanly wrapped around the wire, whereas on the budget tool, and on generic tools, the insulation crimp has ended up piercing the insulation, which is technically a less robust result.

Mate-n-Lok – 6.35mm pitch (TE Connectivity)

Also known as Universal Mate-n-Lok. This a type of connector I have found many times in whiteware appliances, typically on a high voltage, high current connection. It is also often seen in automotive applications, as well as for battery connectors on the RC scene. At 600V it is the highest voltage rated connector I cover here. Terminal rating is 19A.

Its terminals are remarkably similar to the 5.08mm pitch Mate-n-Lok connectors mentioned below, but not quite the same. They’re not interchangeable. As you may have predicted, officially there’s a different tool for them too, so that’s another months spending money if you aren’t keen to crimp them with off-brand tools.

I keep a small stock of these for high voltage applications, as they safely handle a 230V 13A load (UK max socket outlet) without breaking a sweat. They crimp perfectly with the 91504-1 tool mentioned below, despite it not being intended for this purpose. I cannot see any compelling reason for there to be another sodding tool.

58637-1: AWG 14-20 crimp tool

‎926894-1‎: Male crimp pin (AWG 14-20)

926893-1: Female crimp pin (AWG 14-20)

‎1-480698-0‎: 2 position receptacle

‎1-480699-0‎: 2 position plug

Crimping with unofficial tools

I went through all my cheap eBay tools on these. The one that came out on top is labelled SN-48B. The engineer tools aren’t suitable for contacts this large.

Not too bad of a result, however not quite enough force on the wire part, this is a bit of an issue under heavy load as the thermal camera image at the top of this article shows.

Mate-n-Lok (5.08mm pitch) – TE, Formerly Tyco, Formerly AMP

Also known as Commercial Mate-n-Lok. Not a particularly popular connector family anymore but notable as the 4 position variety of these were used on 5.25″ floppy disks as far back as 1976, they were also adopted on 5.25″ PC hard drives, CD-ROM drives and 3.5″ parallel ATA hard disk drives, plus a veritable arseload of other PC related applications. The two and three position varieties are sometimes found on very old computer equipment in design specific applications only.

This connector family includes a rather uncommon member: A single position housing. The contacts’ circular mating surface allows them to swivel 360°

There is a hoard of different tools for Commercial Mate-n-Lok, Pictured below is 91504-1 which has one wire AWG 14-20 and two-wire AWG 18×2 dies (different terminals required).

Key part numbers (AMP)

91504-1: AWG 14-20¹ / 2x AWG18 crimp tool

91512-1: AWG 18 / AWG 20-24 crimp tool

60619-1 : AWG 14-20 Female crimp terminal

60620-1: AWG 14-20 Male crimp pin

1-480426-0: 4 position male housing

1-480424-0: 4 position female housing

¹ Although the singe wire die states AWG 14-20, it’s more like an AWG 14-16 in practice.

“Molex” connector

Molex introduced a compatible connector (for the 4 position variety only) in 1983 imaginatively named “Disk Drive Power Connection System”. Despite their name becoming the vernacular term for this type of connector, they have since exited this market, with all parts either discontinued or near end of life. In my opinion they improved on AMP’s original design, with tighter tolerances, lower mating/disconnection force and a nicer to use tool.

In practice it is unlikely that one would ever encounter a Molex branded connector. Where quality parts are utilised; Mate-n-Lok is the more common choice given AMP’s long term commitment to this family.

Molex terminals have a special retention feature for the locator in the tool, which makes both the tool and the terminals incompatible with anything else. Male Molex terminals are larger at the throat than other makes, meaning they fit very tightly in the housing, so one does not have to manually line up the pins before mating, however because of this they do not interchange with other branded parts. Unless like me you have a propensity for collecting crimp tools and connectors I would not recommend attempting to obtain any of the above.

Crimping with unofficial tools

Realistically you can crimp these with almost anything. If you own the genuine tool, I tip my hat to you. I bet you didn’t pay for it!

Below is a tool known as HT-225D I got for a few quid off eBay a while back:

Does a reasonable job of crimping Mate-n-Lok. It also does a good job of crimping KK 156 terminals (see above).

Mini-Fit Sr (Molex)

A commonly used heavy (50 amp) power connector. It has no frequent consumer uses, but is often used industrially for battery connectors, chargers, large motor controllers, DC power supplies etc.

Despite the similarity of the name to Mini-Fit Jr, that’s about where it ends – these connectors are big. They would make a very a reliable replacement for cigar plugs in marine/automotive applications.

There are three official crimp tools for this family:

63811-1500: AWG 8

63811-1600: AWG 10, 12

63811-3800: AWG 14, 16

Given the amount of force required to crimp these, I’m doubtful there is much in the way of good unofficial crimp tools. Even with 63811-1600 – large enough to bludgeon someone to death with, crimping requires significant elbow grease.

Half measures aren’t generally a good idea when you’re dealing with something that carries the kind of power these are designed for. If you don’t have the tool, I would suggest carefully soldering terminals – unless you’re looking to start a fire. Mini-Fit Sr terminals are near impossible to reliably manually crimp with pliers.

Mini-FIt Sr in recent years has become my go-to for big DC power connections. The one gripe I have is that in the case of the AWG8 terminals – Molex appeared to have forgone the possibility of an insulation crimp. Instead those larger terminals are crimped entirely onto the wire, leaving nothing restraining the insulation, which isn’t as robust as what we end up with on AWG10+ sized terminals.

The AWG 14/16 tool understandably requires smaller terminals, but even with these, you’ve got to open the tool right up, and even then, the terminals just barely fit into it, not so great for usability, In any case, these wire sizes are far too puny for the monster size and carrying capacity of these connectors. If you are using AWG 14/16, it’s because everything else in your system uses a bigger size, and you want something smaller on this one particular occasion. That can make splashing out on this tool hard to justify.

AWG 10/12 are the optimum wire sizes for Mini-Fit Sr.

Micro-Fit (Molex)

These look identical to Mini-Fit Jr, but quite a bit smaller. Not often seen in consumer products but has occasional use in small ‘DC’ / ITX / Automotive PC power supply applications. I’ve also seen them in other unusual applications such as the connector on the DC end of the plug pack for HP Printers and Cisco routers.

63819-0000: Official crimp tool

The extraction tool

Similar in appearance to the Mini-Fit Jr extraction tool, but used quite differently. Read the manual.

Microfit 3.0 terminals crimp fairly well with generic tools:

As always when using generic tools, results are usable but not entirely ideal. The insulation crimp has clearly pierced the insulation, meaning it would be at risk of tearing under mechanical stress. Another issue I noticed is that the contact ends up bent vertically a little too, due to the awkward un-crimped shape of the terminal. This means that you’ll have to bend each terminal straight again before insertion into the housing.

Due to their small size and high current capacity, these have become one of my favourite connectors.

Milligrid (Molex)

2.0mm pitch. Was used by parallel ATA laptop hard disks. Has a few current uses i.e. USB 3.0 internal headers. Compatible connectors are manufactured by many other companies.

E.I. – Economical Interconnect – TE, Formerly Tyco, Formerly AMP

E.I. is most commonly known by its 4 position variant which became the de-facto standard power connection for PC 3 ½” floppy drives, and various other peripherals which installed into 3 ½” drive bays.

Despite its ostensible obsolescence by its original floppy drive use-case, this type of connector lives on as a sundry power connection for a variety of items which people install into their PCs requiring only a small amount of power. Contemporary power supplies still also include this type of connector and adapters to it from other types of connector are still sold in reasonable quantities. Unless some kind of new standardised power connection surfaces which meets this need, it isn’t going away. Clearly someone is still using the other types for some unknown purpose as well, as this product line and all its variants remain in full production.

There is a swag of different tools for E.I. as one would expect for an AMP connector family, but the one most commonly used is 91556-1 which crimps AWG 20-26 wire, with the corresponding sized terminals.

Molex 90331/8619 series

The IBM PC 5150 was the first type of computer to use a connector compatible with these for the power supply connection to the mainboard, and also internally inside the power supply – but from a different manufacturer. I have not been able to identify who originally marketed this type of connector. They were used for the power supply to mainboard connection for PCs up to the Pentium I era. After this they were replaced by Mini-Fit Jr connectors specified in the ATX standard.

The original series came in a number of different positions. On this page I show an obscure 4 position example from the original mystery manufacturer – “P4” which was used for the AC Fan.

Molex only ever produced a 6 position variety of this connector, as this was the only one which came to be incorporated into the XT/AT standard.

The most useful housing is 90331-0001 which comes with all polarising ribs attached, allowing one to snip off the remainder to achieve the desired polarisation. Unfortunately for anyone needing them, they are a little difficult to come by these days.

Sub series

8619: PCB Headers

90331: Housings

2478: Crimp terminals

63811-7500: Official crimp tool

You’ve got a type of connector which I haven’t listed here

Over the years I have received hundreds of emails from people asking me to identify obscure connectors. I didn’t know what any of them were. In summary: If it’s not here, I don’t know what it is. I would have to spend hours looking through thousands of pictures of connectors on re-sellers websites to identify it. I do not have time for this!

From time to time I come across obscure rarely used connectors too. Because we live in a world where there are tens of thousands of different types if connectors, it can take (even me) days to identify these. My general approach is to measure the pitch between the contacts with calipers. You should be able to work out its spacing i.e. 1.0mm 1.5mm 0.1″ 0.2″ (2.54mm, 5.08mm) etc. Enter this measurement as well as the number of contacts (any other visibly obvious features) into either Mouser or Digi-key’s parametric search on their connectors category. You may just find it.