Why are wires (auxiliary, HDMI) so thin? Wouldn’t thicker larger wires transmit a signal more easily?


Why are wires (auxiliary, HDMI) so thin? Wouldn’t thicker larger wires transmit a signal more easily?

In: Engineering

Possibly (as thicker wires have a lower resistance), but they’d also be a lot more expensive. If you make a wire twice as thick, the volume goes up x4. This means the cost of the metal will also go up x4. The thickness they are is fine for most use cases. Just don’t mangle them by wrapping them tightly around your arm! Do yourself a favour and learn how to coil cables properly 🙂

Each of the pins on an HDMI cable or similar actually has it’s own wire that runs to the equivalent pin on the other end.

Thicker wires main advantage is that they allow for a stronger signal that is less prone to noise. However, they are also more expensive in raw materials, and when in a cable with many wires, they get pretty bulky pretty fast. Instead, we use other techniques for reducing the noise on the wires, such as how they’re twisted in pairs in the cable, or the shielding that’s on and in between the wires.

The thickness (called gauge) of a wire depends upon how much current it carries. Cables delivering signals as opposed to power use very low currents. There would be no benefit to making the cables thicker. They would only be more expensive and less flexible for no benefit.

They are as big as they need to be for the specs of the signal-loss and power.

Same as roads, you could turn your street into 8 lane road. You could handle more cars (power) easily but would make the other things more inconvenient. You wouldn’t do this unless there are good reasons due to the cost (money and resources).

On the power end, cables have to be thicker if they are to handle more amperage over more length. Regular HDMI carries maybe 1/100th of an Amp, while power-supplying HDMI carries still less than an Amp. For reference, that cord on your space heater is carrying maybe 10 Amps. That cord isn’t very thick, so think of how thin the wires can be to carry the tiny current in an HDMI cable.

There’s really no benefit in making a cable too thick, little if any gain at a greatly increased cost. For example, you’re not getting any benefit running your phone charger off of a thick 10 gauge cable rated at 20 Amps, over a thinner cable only rated for 5 Amps, because you’re pulling maybe 2 Amps max.

For HDMI cables specifically, the signals are digital. Therefore, the signal to noise ratio (which improves as wires become thicker and higher quality) is essentially irrelevant as long as it isn’t so bad that the receiving end can’t distinguish from a fully on signal from a fully off one. As long as it can, the data is received with complete accuracy.