On Mon, 21 Jan 2019 12:24:20 -0800 (PST), trader_4
wrote:

On Monday, January 21, 2019 at 2:36:13 PM UTC-5, Tekkie® wrote:
In electronics and automotive electronics 5 volts seems to be the standard.
I am curious as to how this was made the standard.

--
Tekkie

5V was the first standard for digital logic going back to the 60s.
It's still common for designs that are not battery powered and
that need very low power.
How exactly they picked 5, IDK. But transistors can work with just
a couple volts, some logic designs had two transistors stacked one
on top of the other, so you'd need about twice the minimum.
Next consideration, you need enough range in a digital design to
reliably distinguish between
a logic level of one and zero. You'd also need that to be agreed on so
that chips from one supplier would work with chips from other suppliers.
Zero wound up being defined as less than .8V,
you needed some separation between that and whatever voltage would
be a one. One I think was above 2.5V and if the logic wasn't malfunctioning
you couldn't get a voltage in between. So, with a one being above
2.5V and needing some internal headroom, 5V is a logical, convenient
choice. Today with improvements, smaller transistors, and the need
for low ultra low power in mobile devices, logic families at 3V and
1.8 v are being used for those applications. Even desktop CPUs are
running down at 3V and below, I think.

This of course is for digital logic electronics. For analog, all kinds
of voltages have been used.

Yup 5v was what the original TTL ran on and those were the most common
IC chips in the beginning. CMOS is more forgiving and will run on a
pretty wide range of voltages.
These days I suspect 5v was chosen because that is what you get from a
USB port and they are everywhere. Before USB became the "go to"
charging port 12v was getting pretty popular and it still is for a lot
of stuff.
It is pretty much #2 in that coaxial power plug you see on wall warts.