Hot answers tagged

72

The colors do not matter electrically. A wire is a wire is a wire, regardless of the color of their insulation. The color of the wire itself may matter when you get into higher voltages, but that's about the type of metal used (aluminum vs copper conductivity, for example). The colors may matter, for readability, adhering to standards, legal compliance. But ...


63

I suspect that there is an ISO standard that bomb makers follow. As evidence of this is the fact that in about 50% of the movies, there is a statement like "remember to clip the red wire and NOT the blue" or some similar statement. SO I suspect that embedded in the ISO document is a standard that indicates the standards for booby-trapping and which wires ...


59

Sometimes, a wire is negligible in terms of its resistance. Other times, impacts of the resistance of a wire can become significant. I'll first show the resistance of a wire, and how you can ignore it in most cases, and then show examples when its impact is significant, and finally a few applications. The Resistance of a Wire Ideally, the formula of the ...


52

Wire colors are like comments in code, even for simple DIY projects. You're talking to your future self. When you take it apart in five years because it stops working, you will have forgotten everything about the original design, so it really helps to follow conventions. For industrial products it is vital to respect norms and conventions because many people ...


48

As you have identified, clipping the correct wire would stop a bomb exploding. So, a bomb maker would ensure that there are many wires, so it isn't obvious which one to clip. They would monitor whether a wire has been cut, and if it is, the bomb would explode. They are bomb makers, after all. They could also add more stuff to detect whether the bomb has ...


46

They are just essentially string to help support the cable. You should be fine soldering the cable. One thing to remember about the cables in headphones is that it is usually enamel coated copper wire. You usually need to heat it up to around 390*C to burn off the insulation before you can make a decent solder joint. The way I do this is to put a large blob ...


41

My guess is the "EN" of the code means "Enamelled" - I.e., it's coated with enamel. That kind of wire is meant for winding transformers, inductors, and electromagnets etc. The enamel coating insulates the wire and stops a coil turning into a single lump of copper. You need to remove the enamel from the ends of the wire, either with a small craft knife, or ...


38

When I was in Afghanistan most bombs (IED's) followed a pattern for the area it was made in. A few bomb makers taught others to make them there way and they taught others and so on. Neatly colored wires were not common in the Pech. Most of the time they were wired so someone watching the bomb could detonate when a target got close. I have been on the ...


38

For a good connection that can withstand lots of movement/bending, use: Solder Crimp terminals (either permanent "butt" connectors, or male and female terminals if you want to connect and disconnect) Screw terminals ("terminal block") (Image from pixabay.com) (Image from wikipedia.org) For a more temporary connection that is quick to add/remove: Use ...


37

My general strategy for dealing with vibrating wires is to provide strain relief. I would consider adding holes in your PCB specifically for wire retention, like in the image below. You can use superglue or a potting compound to adhere the wire to the PCB to further prevent the solder joint from vibrating and failing.


36

There are two effects going on. The heat sinking effect of the connections and the temperature coefficient on the wire. Initially the wire is all at the same temperature. You turn the power on and it starts to heat up. The heating is determined by the electrical power dissipation in the wire, for any given section of the wire Power = Current * Voltage. ...


31

Statistically, there are as many electrons moving in one direction as there are in the 180º opposite so there is effectively no net current. What we know as "current" is the movement of more electrons in one direction than all the others (1D, 2D or 3D through a piece of metal). That's how you can have "tons of free electrons" but no net currents flowing or ...


30

There are plenty of ways of having an active open circuit. Below is just one simple example, using a single PNP transistor. simulate this circuit – Schematic created using CircuitLab The Blue wire carries the power to the Primer/Explosive/Bomb. Current through the PNP is blocked by holding the base high through a resistor and the Red wire. Cut the ...


29

For high currents and thick wires, a gas-tight crimped junction is the industry standard choice. While solder appears to have its advantages, the key issue to keep in mind is the challenge of soldering 1 AWG copper wire, where the thermal conductivity of the wire itself will rapidly draw heat away from the soldering location, and insulation etc elsewhere ...


28

Something like this may help. Just google "solder helping hand"


28

This is a shielding ground wire (or S-GND) which is left bare on purpose, so it makes contact with the foil. It has to be connected (crimped or soldered) to the metal casing of the USB receptacle / plug at the end of the cable. If your device includes a USB connector, S-GND can be connected to the device ground (same as GND), but this connection is optional. ...


26

That is the drain wire that helps carry charge off of the foil jacket and carries more current than the foil can. It is part of the shield/ground of the cable. As far as how to terminate it, that depends on what function it serves in your system. There are several purposes for that shielding: Reducing EMI emissions Reducing EMI susceptibility Defining ...


24

They're not actually magnets, but rather ferrite which is a paramagnetic material. A ferrite bead with a conductor through it is an inductor and so is used as a low pass filter. Typical use is for power cables to reduce EMI (electromagnetic interference).


24

If you really need 3 hands to solder, you're doing it wrong. The need to hold the components or wires together while soldering means that you're using the solder both for mechanical AND electrical connection, and this is a very bad habit to get into. There's an old saying that the difference between military and hobbyist soldering is that the military ...


23

Cables FL1000B20-WHT and FL1000B20-BLU are twisted pair with additional shield. Look at these symbols:


22

Wire colour matters! Not for the current running though the wire but for troubleshooting, safety, and others that may encounter any project. At powerline level voltages, national regulatory bodies have mandated the 'hot' line to be certain colours such as red for power (and orange, black, or brown in multi-phase power) and green or green/yellow striped as ...


20

The answer is hollywood logic. Really, though. If you cut the power, it's dead. If you cut the detonator, it's dead. However, if you cut a wire that looks like the power wire, but is actually connected to some logic that detonates the bomb if it's cut, then it will go boom. If the bomb builder is clever with how the bomb is wired, then it will not be ...


20

In terms of how this can be done electrically, here are some examples: 1) The powered wire may be connected to a normally closed relay. so when power is removed, the relay disengages, causing the normally closed contact to close, setting off the bomb. This however is not a very good scheme if the bomb electronics are powered by a battery, since the ...


19

Short answer: some textbooks are infected with a misconception, the idea that electrons always orbit the individual metal atoms. Nope. They'll also tell you that electrons only jump between atoms when a voltage is applied along the wires. Wrong. In metals, the outer electron(s) of each metal atom have left their original atom. This happens when the ...


18

I would say pogo pins attached to a small peg that can "bite" the pcb, similar to the following but using smaller pegs with one pin in the tip of each one.


18

Something like a T-Tap would fit the bill (see below) It consists of two parts: one crimps onto your 22 gauge wire (the male quick disconnect terminal in the image) and the other part crimps onto the 16 gauge wire. This has the added benefit of allowing you to disconnect and re-connect the LED boards at will.


17

If the question is about small transformers, the above answers are adequate. If the question is about large transformers, i.e. oil-immersed power transformers - that is a whole different game. The metallic conductors in a transformer don't deteriorate with age, but the insulation does. Power transformers are constructed with paper insulation, which has a ...


17

I would solder them and then use three section of shrink-tube. One around each wire and after that a third one to cover all of them. But then I happen to have a drawer full of shrink tube of various sizes so I don't have to buy some...


17

So, the first problem will be that you need to drive that long cable! A 1km long piece of wire is simply a large load, and your microcontroller output will have a hard time changing the voltage on that reliably. Think of the fact that the wire runs through its environment as a capacitor of wire to ground. So, you need a strong output driver. You want that ...


16

Yes, keeping in mind that the rule is that an increment of 3 in AWG numbers represents a halving of the cross-sectional area of a wire. The current capacity is directly related to that area. This means that to create the equivalent of a wire of AWG(N), you need two strands of AWG(N+3), or three strands of AWG(N+5). Three strands of AWG(N+4) gives you some ...


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