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Connectors: A History of Their Technology?
dpbsmith asks: "It seems like a simple engineering problem--construct a device for easily and safely connecting several dozen wires at the same time--but the variety and creativity in their design over the years has been amazing, and, clearly there have been trends, fashions, and styles. In the fifties and sixties, virtually all connectors were roughly similar to the D-Sub design used for RS-232. A stiff, straight pin engaged a springy socket that contacted and bore against it on all sides. There were minor variations in shape and placement; the Amphenol Blue Ribbons (think Centronics), the connectors into which circuit boards engaged, but they were all variations on a theme. I was absolutely astounded the first time I saw a modular RJ-11 connector. Cheap, effective, and utterly unlike anything I'd ever seen before. Who invented these? Western Electric? Recently, we have the USB connector and the Firewire connector, obviously members of the same family (and a cheap-and-cheesy-seeming family it seems); on the other hand, my telephone and my digital camera have connectors that are very small and snap in with a positive lock that must be released with a squeeze, obviously yet another fundamentally different design. What do people know about the design, history, and engineering behind connectors over the years? Is it all hidden away, trade secrets of the connector companies, or is their a story that can be told?"
Bayonet Navy connector (originally
designed for military system applications during World War II)
To make laws that man cannot, and will not obey, serves to bring all law into contempt.
--E.C. Stanton
You can find more info in the Cable FAQ through Google.
My book of more network information than you can shake a stick at says:
Several possiblilities are usually suggested as to the origin of the term BNC:
- British Naval Connector
- Bayonet Nut Connector
- Cayonet-Neill-Concelman (probably the correct explaination somce the connector was named after Neill and Concelman, its two creators)
[Encyclopedia of Networking, v2. Tulloch and Tulloch]
Sorry -- According to the one source no one seemed to bother with (Amphenol themselves) it is, as the coward pointed out, 'Bayonet Neill Concelman' and was named for Carl Concelman (and not Carl & Concelman).
This was an easy find:
http://www.amphenolrf.com/products/bnc.asp
- I am made of meat.
BNC stands for Bayonet Neill-Concelman. The names British Naval Connector or Bayonet Nut Connector are sometimes used but are not correct. The connectors were named after their creators; Neill designed the "N-type" connector and Concelman designed the "C-type" connector. The BNC is a hybrid "N/C-type" with a mechanical extra; the bayonets.
The UK AC plugs may be large, but they are safe, which is a lot more than I can say for the horrible US AC plug design. I visited the UK last year with a bunch of US multi-voltage video equipment. My British hosts were stunned at how bad the US plug design was, and how easy it would be to shock yourself as you inserted or removed one. The hot blade is exposed with AC power on it - if your finger should slip, you get zapped.
The UK plug design is plastic along the length of the blade, and only the end is metal. By the time you see the metal tip of the blades, the circuit is already broken.
"How perfectly Goddamn delightful it all is, to be sure" Charles Crumb
The USB mechanical spec calls out that the USB logo be molded on one side of the cable in such a way that you can feel it and the other side be smooth. The logo is specified to go up.
:-(
And all was good.
Until manufacturers could save $0.02 by putting their jacks on upside down or sideways. Now you have a bunch of nicely polarized cables that you can orient blindly in the mess of cables, but have no idea which way the jack is oriented.
(Yes, I have an upside down computer from a vendor that knows better and screwed me for $0.02.)
Here in Europe, the pins are often sheathed in plastic tubing at the end nearest the plug body. When the plug is inserted into the wallbox, the tips of the pins don't make contact inside the wallbox until the sheathed part of the pins has already started to enter the holes in the wallbox.
So it's impossible to touch the metal part of the pins when they are live.
The crufty among us will remember the ultimate minimalist connector. The original ethernet (thick wire) used a large coax cable as the backbone. You connected to it by drilling a tiny hole and inserting your tap into the cable in such a way that it made contact to the core and shield without shorting anything and wiping out the whole network.
:-)
It really made 50ohm BNC look good when it came out.
And I'll take the RF and audio side. :)
1/8" stereo audio - Cute, impossible to insert incorrectly, noisy (electrically), easily broken.
1/4" audio - Big and ugly, until you get used to it. Then you get 18 hours on a modular synth and learn to love them.
RCA - What, like 100 years old or something? Classic, and easy to use.
XLR - Good idea, bulky, but positive contact, locking, and keyed. Pro shops use this for a reason.
UHF (PL-259 / SO-239) - Ancient, gives an impedance spike on the line, fucking impossible to solder with anything less than a 150 watt iron.
BNC - Beautiful. Love this one. I'm converting all RF gear in my shop to BNC, bit by bit. Power handling isn't quite up there, but you can go N for that.
N - Tough, reliable, smooth (impedance-wise), and dead simple to install once you get the hang of it.
F - KILL THIS FUCKING CONNECTOR. Yes, I know it costs you $0.03 per unit, but it's annoying and the inherent 'center conductor IS the pin' is remarkably irresponsible. I'd feel so much better if that cable TV jack on the wall was a BNC.
Hey Taco! Looks like you're using the "infinite monkeys and typewriters" scheme to generate Ask Slashdots again...
Open it up, and solder in some normal connectors...
The reason why 802.11b equip. has these funny connectors is becuase the FCC mandates that wireless equipment have "difficult to obtain" connectors.
If you don't want to solder, then go to http://www.fab-corp.com/ and see if they have what you want.
I did sound on a touring edition of a broadway show back in the early 1980s. The system supplier was Masque Sound, who did most of the shows on Broadway. The bad habits of the stagehands forced the companies to do things a bit differently -
Every single XLR cable was female - on both ends. Every XLR panel connector was male.
The reason was that the stagehands insisted on pulling cables out by the cord. Apparently, pressing the little tab was too much work. Masque found that the female XLR would be the one to break, so they used females only on cables, because they were easier to repair. They would go through and replace every female XLR on every a 32 channel mixing board.
Even more bizzarely, they used 2 prong polarized AC cords for speaker connectors. The speaker cabinets had duplex outlets on the back.
"How perfectly Goddamn delightful it all is, to be sure" Charles Crumb
The vast majority of the electrical connectors you see are either male of female. They're all built just to mate with its complement, which raises parts storage issues as well as restricts how things can plug into eachother. I got a hold of genderless-mating modular connectors that can snap together in many configurations, and have no concept of 'male' or 'female'. They're apparently made by Anderson Power Products. I have a few pictures of their smaller connectors here. Connectors like these would be GREAT for daisy chaining DC power sources and/or building quick-disconnect battery charging harness, since their design maintains polarity regardless of the "direction" of the connector (supply to supply, battery to battery, battery to supply, etc)
Making mouse and keyboard identical was stupid.
No, what was stupid was not just running all wires to both connectors. The only difference between the two is that the keyboard clock and data are run to two pins on the keyboard (and not connected on the mouse) connector, and the same thing for the mouse. Just run all the traces to both and you can plug either in to either port.
Choosing to save money by not putting a shift register in the printer was one of the most unfortunate decisions in the history of personal computing.
It made sense at the time.
A long, long time ago, adding a shift register to a printer would have been very expensive.
(This was in the days of 7400-style chips, where six (count 'em, six) NAND gates fit on one 16-pin DIP.)
It made a lot more sense to send bits from a register on a minicomputer over parallel wires to a register on the printer, rather than converting them from parallel to serial and back again.
In addition, the parallel line returned OOB signals back to a register on the minicomputer (e.g., paper out).
Injecting these signals into a serial data stream would have been prohibitively expensive.
Finally, many printers had no buffering capability, again, because of the expense.
That is, a character would be received, then printed, then the printer would signal its readiness to receive the next character.
(I used a Centronics brand dot-matrix printer that behaved this way.
(It may have been able to buffer one character ahead, but that was it.))
Now, all of this occurred before the personal computer revolution.
So why did early PC designers decide to use the D-15 connector parallel printer port adaptation of the Centronics printer interface?
Because that's what printer manufacturers were making.
At that time, the majority of printers were still being sold for use with minicomputers.
If they had come up with a new interface (e.g., serial), then printer manufacturers would have had to make two different models for each printer, one with the old Centornics interface, and one with the new serial interface.
Also, it was easier for the home hobbiest to interface to a parallel port than to a serial port.
(I remember interfacing my old KIM-II (which had no printer port) to a printer with a Centronics port.
It required a Centronics connector, a cable, a socket for the KIM board that was similar to an ISA or S-100 style socket, and ZERO additional logic chips.)
I do agree with you that the marketplace got "locked in" to using parallel for far longer than was necessary.
But I disagree with your assertion that the decision to go parallel was a "suboptimal solution" at that time.
Now, today, it makes no sense to have a parallel interface for any peripheral that I can think of, and, in fact, parallel is being phased out for peripheral interfaces.
Witness serial ATA for hard drives, and the removal of the parallel port from several modern motherboard designs
(along with other legacy interfaces, such as the serial keyboard, mouse, and modem connectors, not to mention ISA).
(Not all parallel is going away; it still has a place, e.g., between memory and the CPU.)
As time goes by, the older stuff goes away, to be replaced by newer stuff that is more appropriate for newer times.
But, at the time, it made sense to do it the way that it was done.
Those who sacrifice security to condemn liberty deserve to repeat history or something. - Benjamin Santayana
So, here is what I know. Not everyone here knows their cables or connectors nor do they need to. Here are some simple things to help you out with.
RJ stands for Regents Jack. RJ11 is your typical 2-6 pair telephone jack. RJ45 is your typical 4-5 pair Ethernet pin jack, also gets used for DS1s.
BNC is a Barrel Node Connector. BNC gets used on test equipment, older coax cable NICs for thin or thicknet. Also DS3 twinax cable interfaces. That screw in on the back of your TV set? F-type.
Tons of pretty pictures;
http://www.cmsa.wmin.ac.uk/~alan/compo
Molex appears to have a nice connector tutorial for you to check out. I need to look this over myself;
http://www.molex.com/training/bce/gstoc.
Get yourself a Molex catalog. Every type of cable connector you can imagine. Go to their products page and browse around.
http://www.molex.com
Do not forget Amp, even though their web presence sucks (or last time I looked)
http://www.ampnetconnect.com/
Random cable interfaces, with some pictures;
http://www.peakaudio.com/CobraNet/Netw
Cable Types for 3Com Products
http://support.3com.com/infodeli/tools/
Unix Serial Port Resources: Sun Serial Port & Cables Pinouts
http://www.stokely.com/unix.serial.port.
IEC has standards, like that power plug on the back of your computer -- an IEC 320 plug.
http://www.iec.org/
Your typical U.S. three prong power plug is an NEMA-5-15P (P for plug), and the receptical is a NEMA-5-15R. Here are some charts with pretty pictures;
http://www.leviton.com/sections/techsu
http://www.quail.com/locator/nema.htm
SCSI connectors, pinouts, and protocols, and some IDE/ATA stuff too;
http://t10.org/
Do not forget about the Fiber Channel and HIPPI;
http://www.t11.org
PCI card interfaces;
http://www.pcisig.com/
EIA/TIA;
http://www.tiaonline.org/
Whoa, I just found this... standards for wiretapping?;
http://www.tiaonline.org/standards
Cisco, always a great place to look and learn. Common LAN interfaces from what I see;
http://www.cisco.com/univercd/cc/td/doc/pro
More Cisco, including V.35 and X.21 pictures;
http://www.cisco.com/univercd/cc/td/do
Arg, I had to repost this because Slashdot says, "Your comment has too few characters per line (currently 26.9)." That sucked and needs to change.
If you have more references, please let the world know. I know stuff, you know stuff. Put your stuff here.
There are other RJ-series connectors other than RJ-11/12 and RJ-45.
..RJ11: Normal (1 pair) home phone jack, having 2, 4 to 6 pins
RJ (Modular Connector Jacks (female), Plugs (male)) types:
RJ12: Has 3 pairs of pins: An RJ-11 using 3 pairs of wires
RJ14: Has 2 pairs of pins: An RJ-11 using 2 pairs of wires
RJ22: Normal (1 pair) hanset jack, having 2 to 4 pins
RJ25: Has 3 pairs of pins.
RJ45: Has 4 pairs of pins. Used with RS232, 10BaseT, EIA568.
RJ48: Has 4 pairs of pins. Four voice circuits, used with T1/E1/ISDN.
Happy Fun Ball is for external use only.