Connectors for PC Equipment
This is a guide on connectors for pc equipment.
RJ-11 & RJ-45
Now, beginning with the RJ-11, this is the traditional connector for a phone cable and it contains four internal wires in total in two sets of twisted pairs. So there would be little metal contacts in the physical connector itself that would make contact with the internal copper core of the wire. And an RJ-45 is the traditional connector for an Ethernet cable, and it contains eight wires in four sets of twisted pair.
Now physically, they look fairly similar to each other, but as you can see by the graphic, the RJ-45 is certainly wider than the RJ-11 because of those extra wires. [Video description begins] The presenter points to a graphical representation of an RJ-11 and an RJ-45 connector. The RJ-45 connector is twice as wide as the RJ-11 connector. [Video description ends]
In terms of some of the characteristics for the RJ-11, the RJ actually stands for Registered Jack and that tends to be the term that we all use on a daily basis. We might ask, where is the phone jack? And it has what's known as a six position, four connector configuration, and that means that it actually can accommodate six wires. There's six little channels in the physical connector itself, but for a phone connection, only four of them are used. So this is known as a 6P4C configuration. But you might find some specific equipment that actually does use six wires, but for the standard phone lines it was only four.
So this is primarily used for voice and data applications, of course, again, our standard phone systems, but data, of course, over a modem. Or if you have a asynchronous digital subscriber line or ADSL lines, this also used your RJ-11 jack and it supports a maximum of 24 megabits per second.
Now for the RJ-45 characteristics, we have an eight position, eight connector configuration. So in other words, again, there can be eight wires in total but all eight are being used for the RJ-45. So this was known as 8P8C and of course, this is primarily used for data applications, regular Ethernet networks. And at the moment, it supports a current maximum bandwidth of 10 gigabits per second.
RS-232
In this presentation, we'll take a look at the physical connectors for RS-232 ports. And RS-232 itself just defines a standard for serial communication or transmission of data one bit at a time. And this was most commonly implemented with a DB9 connector, using nine pins in two rows, one row of five, one of four.
Now the DB stands for D sub, and the nine indicates the number of pins. But the letter D actually indicates the fact that if you take this connector and stand it up on its edge, the metal ring, if you will, surrounding the pins has a trapezoidal shape that actually looks a little bit like the letter D. That's where they got that.
Now, it can be used with other connectors, depending on the device, such as printers. They typically would have a 25-pin connection, one row of 13, one of 12. But for this connector, this was most commonly referred to as simply a com port, com for communications.
So looking at the characteristics, RS actually stands for recommended standard. And again, this was just most commonly used for devices with simple configuration or minimal data transfer because it was just one bit a time. So a mouse, an uninterruptible power supply, an external modem, and even some early PDAs for synchronization often used the com port.
So RS-232 itself, again, does define some of the electrical characteristics and the timing of the signals. But the physical connector was most often just that DB9 connector. But it's very unlikely that you would find a com port on most modern systems. They have been almost entirely superseded by USB, but you may still find some on some older systems.
BNC
The next physical connector that we'll take a look at in this presentation is the Bayonet Neill-Concelman Connector, or BNC.
Now this is traditionally used with coaxial cable but not the same cable that's used for cable TV or cable Internet. This was actually used in early Ethernet networks and it was known as 10Base2. Also nicknamed Thinnet because it was quite a bit thinner than the coax cable used for cable TV or cable Internet. And the 10Base2 indicated 10 megabits per second base band transmission. But the 2 indicated that it went approximately twice as far as 10BaseT, which was the standard twisted pair Ethernet cable at that time.
Now it has twist-lock ends which, again, is different than the cable TV cable. That has a threaded connector so you literally screw it onto the connection. This one would just be inserted over the connector, and then there's a cylinder that could twist which would lock it into place. And this was sometimes also referred to as a British Naval Connector, but that was also just a nickname.
Looking at some of the characteristics, it was dependent on the equipment, but it's commonly used with radio frequency equipment. And this is actually where the British Naval aspect comes into play. [Video description begins] Radio Frequency is known as RF, for short. [Video description ends] A lot of radio signalling equipment that was used by the British Navy did use this connector. But a lot of testing or diagnostic equipment, or really any kind of industry specific instrumentation, may still use BNC connectors. And really any device that carries video signals, a common example might be a closed-circuit TV system.
And the connector itself is designed to match the resistance or the impedance characteristics of the cable being used, and most coaxial cable has an impedance of 50 or 75 ohms. So the idea was that the connector itself should not add any resistance to the cable. So as far as the signal is concerned, the connector is no different than the internal copper core.
So again, you probably won't find BNC in an Ethernet network anymore. But certainly some of that industry-specific equipment and various types of video equipment will likely still use BNCs.
RG-6 & RG-59
In this presentation, we'll take a look at the RG-6 and RG-59 physical connectors. And in both cases these are used with coaxial cable. But for both of them it's still a thicker, heavier gauge coaxial cable than what was referenced in the previous presentation, when we talked about what was known as Thinnet.
So RG-59 is still used with coax cable that is a lighter gauge wire with thinner insulation and less shielding than RG-6. But still heavier overall than that previous Thinnet type of coaxial cable. RG-6 is traditionally used with coaxial cable as well, but it's a heavier gauge wire with thicker insulation and more shielding.
So looking at some of the specific characteristics for RG-59 and, of course, for 6, the RG stands for Radio Guide in both cases. And this was used most commonly for cable TV in earlier installations or maybe for closed-circuit TV systems. The smaller conductor however could not achieve the same signal quality as RG-6. And its lesser shielding, although it was adequate for the lower megahertz value of analog transmissions, it's not really adequate for the higher gigahertz levels that we find today. So it's a poor choice for modern digital TV or Internet.
So the RG-6 then, is what you'll find most commonly used for modern digital cable TV or Internet service over a cable modem. It has a larger conductor that provides better signal quality. And its improved shielding was adequate for the higher gigahertz levels of digital signals. So this is a good choice for modern digital TV or Internet and likely what you would find in today's implementations.
USB
In this presentation, we'll have a look at the connectors used with the Universal Serial Bus or USB. Which these days is, of course, the most widely used connection for most of the devices we encounter today. And it superseded many different interface connections from the past including your mouse and keyboard, your printer, scanner, or multi-function unit. Any kind of external storage, maybe a game controller or a camera, and again, just a multitude of other devices that all use USB now.
Now it's designed to carry both data and power over a single connection. So of course, it's not just the data connection, but if it is some kind of chargeable unit, your USB connection will also charge it. And there are currently three generations: one, two, and three. And you can see that one and three had a few sub-variations, if you will. [Video description begins] The presenter points to the three generations of USB that are listed. USB 1 and USB 3 are listed as 1.x and 3.x. [Video description ends] But ultimately, they invariably just increased the speed and the capacity of the interface.
And almost every USB device is hot-pluggable, meaning that you can just plug it in and unplug it at anytime without having to shut anything down. And any device can use any receptacle that fits, of course, because there are different connectors but as long as it fits, it will work and in most cases, there is little to no device configuration. Now, that does depend on the device but with modern operating systems and modern devices, in many cases the device will be identified and configured automatically.
So in terms of the variations for the connectors, there are the standard connectors that were introduced generally with USB 1 and they're simply referred to as type A and type B. And in most cases, your type A was the computer interface and type B was the device interface. Now this was most commonly found in printers, or scanners, or multi-function units. So the type A in graphic is the one on the left, the rectangular one and the type B is on the right and it's a little more square but it's knocked off on the top corner so that you can't get it in upside down. [Video description begins] He points to a photo of a Type A and a Type B connector. The type A is a flat, wide connector, while the type B is square with angle edges on top. [Video description ends] But that was certainly the most common type of interface, again, for printers, scanners, and multi-function units.
Then the mini was introduced and again, this had mini A and mini B. And in fact, a mini AB which could accommodate either, but typically the configuration of A was the end that connected to your computer and B was the end that connected to the device. But again, AB actually could accept either. [Video description begins] The Mini A has a rectangular shape with angled bottom edges, while the Mini B has a straight rectangular shape. [Video description ends] And as its name indicates, it was a physically smaller connector that was most commonly found in cameras or really any kind of smaller device where space is limited. It didn't have any effect on the transmission rate, or the power, or anything at all, it was just physically smaller.
Then we also saw a micro. This again, had A and B, where A was typically connected to the computer, B to the device. And micro also supported AB, where you could use either, and this again, was physically smaller than mini. [Video description begins] The Micro A has a straight rectangular shape, while the Micro B has a rectangular shape with angled top edges. [Video description ends] Now, this is most commonly found in newer mobile devices, maybe a cellphone, a GPS, or a newer PDA, but again, just a little bit smaller still than mini.
Now, micro B 3.0, as its name indicates, is only available with USB 3.0 devices, and it is a physically different connector. So it's not backward compatible with USB 2 or 1.x devices, it's kind of pinched toward the center. So it only fits in that specific connector type, but it was designed for the current high-speed requirements of newer devices. And it is still smaller than the type A but a little bit larger than, say, the mini. It's somewhere in between.
And finally, the newest is type C. And I think you will likely see this moving forward, it's a symmetric oval shape that is reversible which is very nice. It doesn't matter upside down, downside up with this connector. So that's the first USB connector that actually offered that capability. It's comparable in size to that of mini, so it's still fairly small. It's a little bit larger, but again, not as large as the original type A, and it supports the highest speeds currently available, up to 10 gigabits per second.
So again, I think that you'll probably find, this will be the dominant connector for most devices moving forward. But as long as you still have a device that requires one of the earlier connections, of course, you will still need to keep that cable. Even though this one is probably one of the best connectors, it's not backward compatible to earlier versions. It's only usable with USB 3. And again, the physical shape is different than every other connector before it.
DB-9
In this presentation we'll look specifically at the DB9 connector, which is most commonly implemented with simple, serial devices, such as a mouse. Maybe an early PDA and often a management interface for com ports or RS-232 devices such as an uninterruptible power supply, a router, or diagnostic equipment. [Video description begins] An Uninterruptible Power Supply is also known as UPS, for short. [Video description ends] So you would simply connect the device to your computer and this would allow you to use some kind of interface to configure the device.
As for its characteristics, the DB stands for D-Subminiature, or D-Sub, or just DB and the D is actually drawn from the trapezoidal shape of the connector. If you stand it up on its edge, it looks a little bit like the letter D. And a DB9 is always a serial data transfer, meaning that it transfers one bit at a time, hence the reason it was typically used for fairly simple devices. And specifically the DB9 uses a 9-pin configuration. This is of course what the nine means and it's always in two rows. One of five, one of four.
Now, this is a fairly old interface, so this has been largely superseded by USB or other interfaces. So it's rarely used with modern devices, but you may still find it on some older laptops, for example. They were very commonly used to configure devices such as uninterruptible power supplies and routers. So it's not extinct, but certainly pretty rare these days that you would find a DB9 connector.
Lightning
In this presentation we'll take a look at the physical connector for a lightning cable which is a proprietary Apple connector for use with an iPhone, an iPad, or an iPod.
Now, it's probably used most often to charge your device but it also supports data transfer and audio. So that if of course, you are synchronizing it to your computer, it copies all the data over. And if you plug it in to something like your car audio system, it of course transfers the audio as well.
In terms of the characteristics, it's an 8-pin connector, that was introduced with iPhone 5 and iPad 4 as a replacement for the 30-pin predecessor. So it's significantly smaller than the previous connector. It's not even a centimeter across. And it also has a reversible connection which is very nice, it doesn't matter if you put it in right side up, or upside down. But of course it is significantly physically different.
So it's not backward compatible to any of the older devices. But it does work with many newer Apple devices such as a magic mouse, keyboard, trackpad, or pencil. All of them can be charged using this cable. Airpod headphones can be charged as well, and Beats headphones and/or speakers can all use the lightning connector.
SCSI
Now in this presentation we'll take a look at some of the connectors used with the Small Computer System Interface, or SCSI. And this can be a little challenging, in terms of identifying the connector. Because quite simply, there is a wide variety of connectors, depending on the device. But they do have some characteristics in common.
Most SCSI connectors do tend to be fairly large. The actual connector end, itself, might be two inches in width, as opposed to something like USB, that is barely a little more than a centimeter, so a lot larger. And they also tend to have very high pin counts. Sometimes 50 or 68 pins might be fairly common, so the pin configuration would look quite densely packed. But SCSI itself is a bus technology, meaning that devices can connect to the central bus and then are daisy-chained.
So another giveaway is if you are talking about an external peripheral device, such as a printer or a scanner. Then what you might often find is a SCSI in and a SCSI out, so that you can just literally go from device to device to device. That would certainly be a giveaway that it is a SCSI interface. And then all of those devices do need to be controlled by a host controller which is typically built into the motherboard or as an expansion card. So you just connect all of your devices to that one interface.
Looking at some of the characteristics, SCSI was most commonly used as an interface for hard drives but it does support a wide range of other peripheral devices. In terms of the hard drive connections, the reason that SCSI was a little more popular, at least when it came out, was quite simply because it was faster and it supported more drives. Its competitor in earlier days was IDE, Integrated Drive Electronics. Which only supported two devices on a single cable and it was not as fast. So in any kind of system where you needed more hard drives and faster hard drives, then SCSI really was the choice.
Now it has undergone a number of revisions to improve its specifications in terms of the data transfer rates. We saw things like fast, ultra, and wide come out and then versions 1, 2, and 3. And various combinations of those were available, but each one of course just improved the specifications. And it was able to support up to eight devices in total. So including the host controller in that daisy-chain configuration, [Video description begins] These daisy-chain configurations were present in early implementations. [Video description ends] and then up to 16 in later revisions. So again, it was the controller counting as one, then seven more devices in the original implementation. Or the controller plus 15 more in later.
So as such it was a common interface in server systems that required more drives or more peripherals. It was not nearly as common in client systems. And that might still be the case today. You might still find servers with a lot of SCSI devices, but standard desktop systems I think would be pretty rare. There might still be some dedicated or specific work stations that connect to any type of device that is just very specific for a particular purpose. And that might still use a SCSI interface, but for most desktop systems at home or even in a corporate environment, SCSI has largely been superseded by interfaces such as USB, but it's certainly still in use these days.
eSATA
In this presentation, we'll take a look at the connector for the External Serial Advanced Technology, or eSATA interface. And this is simply an extension to the serial ATA interface that allows for SATA drives to be attached externally, hence the E.
Now the physical connector itself is quite similar to the internal connector with one minor difference. You can see in the graphic that black line that is just going across horizontally. That is essentially where the connection is made. [Video description begins] The presenter points to a black section in the center of the sample connector that displays. [Video description ends] And on an internal SATA connection, there is a small notch on the right-hand side facing down that kind of makes it look like a letter L, if you were to turn it upright. The eSATA does not have that. It's just straight across. So that's how you can distinguish them. But they're just about equal in size, and overall SATA connections are rather small, particularly compared to its predecessor, IDE. It's not much larger than a standard type-A USB connector. It's maybe only a little more than a centimeter across. But, it might be a little thicker or a little taller, I guess, than USB.
Now, SATA itself largely replaced the IDE interface of hard drives in client systems. Primarily because it supported much faster data transfer rates than IDE and it was also easier to get more drives because of that small interface. Now, IDE did allow you to share the cable so that you could have two devices. But typically, there were only two ID interfaces in most systems. So you could have a maximum of four. But because of the small size of the SATA or eSATA connections, it was very easy to have four, six, or eight, or even more in a single system, particularly if you purchased an expansion card.
Now, in terms of the eSATA characteristics, again it's just an alternative for attaching external drives. It did actually have Faster data transfer rates than USB 2 or FireWire, which were very common, but it does require a separate power connector. Now, that in itself wasn't all that uncommon either. A lot of external hard drives, typically the larger ones, the physical larger ones did require their own dedicated power as well, even if it was USB 2 or FireWire. And it uses a point-to-point interface so, unlike a BUS, there's no daisy-chaining of devices. So, if you have, let's say, three physical external hard drives, you would need three physical eSATA cables. So multiple connections are typically available. However, it would likely require an expansion card, so that you have the connections on the back of your computer.
Now, all of that said, USB 3, which is common these days, matches or exceeds the transfer rates of eSATA. So it would not be uncommon, of course, for more modern external drives to simply be using a USB 3 interface, but it's not uncommon to still find eSATA connections either.
Molex
Now, there are varying types of connectors dependent on the device. But some common examples include the power connections for hard drives, optical drives, floppy drives, the entire motherboard itself, your CPU or graphics card, or fans.
Now in almost every case, the connector is a white plastic tip with just metal pins inside of it. But you might see some black ones from time to time, that's not uncommon. But they're usually easily identified by the colored wires coming out of them, which are almost always red, black, and yellow.
Now, there are some different characteristics, again, depending on the connector. But in general, you'll see some 4-pin connectors in a single row, which is most commonly used for hard drives or optical drives. And then you will likely see a 4-pin connector in 2 rows, so it looks square, which is most commonly used for the CPU or a graphics card. And then a 20-pin connector, which is most commonly used for the motherboard.
Now, that one would have some additional colors of wires. Because there are a number of different components actually drawing from that single connection. So of those 20 pins, you would see more than just red, black, and yellow. But it's all just a single connector anyway. You really just can't attach that connector anywhere else but directly to the motherboard.
Now, all Molex connectors are used for power only. There's never any data over a Molex connection. And it's almost always used internally only. And the Molex connections themselves are extended directly from the main power supply of the PC. So if you were to take the cover off of a computer, most commonly, the power supply might be up in a top corner. And then coming out of the back of it, you'd see a bunch of bundled wires that all terminate with those Molex connectors.
Now, it would depend on the make and model of the power supply with respect to how many connections you would have. But it's not uncommon for there to be more than what you would generally need. They essentially err on the side of caution so that you quite literally don't end up with not having enough connections. So you typically tend to see maybe four or more hard drive or optical drive connections, at least two in most cases for the CPU or a graphics card. You might only find one, again, depending on the model. But certainly just a single one for the motherboard, you wouldn't ever really see two of those. But again, it's not uncommon just to have extras. So don't worry if you do end up with connections that just aren't being used, that's perfectly fine.