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125

It stinks It leaves soot and partially burned plastic on the wire and between the strands - those makes solder joints more difficult to make and less reliable. It is difficult to control how far back the insulation melts. Some insulation materials will soften and sag further back from the burned place, compromising the insulation. Lighters are hard on your ...


89

Like Jessica Rabbit- because they are drawn that way. Wire production involves pulling (drawing) the wire through successively smaller dies (often with annealing in between). The dies are most easily made with round holes (they are typically made from very hard materials such as diamond). Not all wire is round - rounded rectangular wire is sometimes used ...


75

We old farts mainly do it to show off our skills to young whipsnappers. Few things are as satisfactory to see a student or new employee ogle at how, with just some side cutters, you quickly remove the insulation from a dozen wires. Also you don't want to breathe toxic fumes or have burn residue on your wires.


71

Digital signals are highly susceptible to the noise generated by rotating the plug. For audio, these noises (cracks) are rarely audible unless they last longer than 50us (simply because of the fact that we're unable to hear frequencies over 20kHz). So, the cracks becomes audible only when the surface of the connector has deteriorated enough that the period ...


69

There are a few industry approaches to this. The first is molded cables. The cables themselves have strain reliefs molded to fit a given entry point, either by custom moulding or with off the shelf reliefs that are chemically welded/bonded to the cable. Not just glued, but welded together. The second is entry points designed to hold the cable. The cable ...


58

Summary When entering and exiting the idle state, the polarity is important and swapping the D+ and D- lines will cause problems. Data Transmission USB data is NRZ-coded such that "One" is represented by no change in physical level, and "Zero" is represented by a change in physical level (see figure below). Therefore, inverting the signal (for example, by ...


48

If you just ignore the POE 48 Volts in the image below, you can see Ethernet uses transformers on both sides. This way there is no need for common ground as long as the common mode voltage stays below 1500V generally. The isolation specification of the transformers. And as a bonus you now also know how POE works. (802.3at) However, CAT6A often has a ...


48

You would do a BERT (bit error rate test) on the cable. Better yet, look at the eye diagram at the far end of the cable. HDMI is a digital format, which means that there's a threshold effect — cable quality does not affect the picture quality at all until it gets so bad that it actually causes bit errors. "Premium" cable is (supposedly) built to ...


44

There are ribbon cables with twisted wires: Every few cm, there is a flat section to allow attaching an IDC connector. Looking at two product drawings it appears to be pretty typical to have 50 mm of flat cable out of every 500 mm.


43

When you move away from circular cross sections you run into two significant problems: First, corners would exert more pressure against adjacent things, and are more likely to result in insulation damage. Second, for high frequency use the skin current effect would result in higher impedance in a cable with the same cross sectional area but with corners. ...


42

red = +5 V white = D- green = D+ black = ground (Page 89 of the USB 2 specification) edit (after reading the other 649 pages) OK, that's from the formal specification. Reassuring, isn't it? It can even get you an accepted answer. You can feel it coming: there's a but. This is from page 94. At first sight it seems to confirm what I said, but then ...


36

Coax was used for its controlled impedance, its bandwidth and its self-shielding properties. Sure, twisted-pair wiring has existed for a very long time, mostly used to carry audio frequencies in telephone wiring. That isn't where the technical advancement was required. In order to compensate for twisted-pair's lossiness and impedance issues, major ...


36

I2C is not designed to be used over long distances but I know of several applications where it is actually used over a distance of about 2 meters. I also know of one case where they had issues with that and it was eventuelly fixed by fixing ground loops I believe. To be sure that it will function, you should use an I2C bus extender like the P82B715. ...


34

Flexibility A round cross section allows the wire to flex in any direction equally.


31

The ends of wires in a cable get soldered to the left end of that assembly. Then the assembly is placed into a mold and hot plastic is injected around the wire to form a handle for the end of the cable. The plastic molding often includes a flexible strain relief for the cable. Typical result: Often times the best way to understand something is to take it ...


30

This must be British. For them "fit" means something like what we would call "install". For us, "fit" means how well something fits, meaning how good it is at mechanically going into the right mounting holes or whatever, or how effective it is overall in the role it is being used in. In this case "no-fit" means "do not install". This is often done when a ...


30

Because using the correct tool gives you a better result with precise strip lengths without the risk of leaving combustion products all over the wire which will adversely effect solder-ability or conductivity.


30

I assume this is due to insufficient shielding to get a USB 3.0 link? It's more likely that you simply introduce an impedance break so significant by separating the conductor pairs of the superspeed conductors that communication can't properly take place. What is the most likely cause for this failure, and how to avoid it in the future, if possible? As ...


27

Why is Ethernet not grounded? There are two reasons: 1. It would create a ground loop between devices 2. The device would also be more susceptible to ESD which is prevalent in cables that are being moved or handled (from triboelectric charging of the cable) The reason Ethernet is more susceptible to a ground loop is because: The loops could be much ...


27

HDMI cables are tested at an Authorized Testing Center (ATC) and given a certification based on how much bandwidth they can handle (which is to say, how high of a frequency signal they can transmit without the signal degrading beyond some parameters specified in the standard). Signals in a cable degrade. The signal that is input to the cable is not ...


25

The size of the cables isn't due to the size of the copper conductor inside them - that's a fairly small part of the cable. Most of the bulk comes from the electrical insulation. Electrical cable needs to be insulated so it doesn't short circuit. The higher the voltage, the thicker the insulation required. Your thick mains power cord is insulated to ...


25

The normal cable ratings assume that the wire can adequately disperse heat generated in the cable due to the current flowing. If you coil it up and use close to the maximum rating then it stands a good chance of melting the plastic insulation and then causing a short.


25

USB is defined at several data rates. 12 Mbps is called "Full Speed" 480 Mbps is called "High Speed" 5 Gbps is called "SuperSpeed" 10 Gbps is called "SuperSpeed+" A USB product marketed as "High Speed" should be conforming to at least the USB 2.0 specification, and capable of carrying a 480 Mbps USB High Speed signal. Some of the specifications that ...


24

Wireless technology is great and can be used in all sorts of scenarios but it's complex and hard to design for. Wires are in fact superior in many ways. ( Taken from: Essentials of Short Range Wireless Standards ) With wires: Range is not an issue - just add more cable Latency is excellent - what goes in one end appears immediately at the other They're ...


23

Other common terms used are "no placement" (NP) or "do not place" (DNP) but "no fit" would fall into the same category. It means the circuit board (PCB) has pads where a connector may be placed, but when you receive the board it won't have a connector installed. It will be up to you to source the connector and install it youself if you require it.


22

Wired connections have some properties that wireless connections don't: Robustness: a wireless connection can be subject to various forms of interference (think to microwave ovens) and obstacles, that can affect the quality of the received signal. Latency: wireless connections make a large use of acknowledge signals and error checking codes, due to their ...


21

Considering the number of lightning strikes on or near power lines, power going out as a result of one is actually quite rare. Overhead power lines do have cables that run above them mostly for the purpose of catching lightning strikes. These cable are then periodically grounded at poles. Lightning is a massive current surge, and sometimes stuff happens. ...


21

I assume the plug uses screw terminals. In this case, and if you use stranded wires, use wire ferrules to protect the wire strands from breaking. The wire must be rated for 16A usually. Ensure that the strain relief is tightened properly. Make the earth/PE wire little longer than N/L. This is to ensure that the PE wire stays connected longer than N/L in case ...


20

Whether it produces good results or not, wire insulation is one of the worse things to set on fire because "modern electric wires commonly use PVC plasticized with linear Phthalates" as insulation1. The National Center for Biotechnology Information states: With its high content of chlorine, PVC is frequently branded as a major chlorine donor and ...


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