Re: "Barrel" connectors

On 6/16/2025 8:59 AM, legg wrote:

They're not infinitely variable.

No, but there are a score or more different configurations
(neglecting length variations).  And, many of them are
"close enough" that you can get the wrong plug to mate
and still not make electrical contact.
[And, the mechanical aspects still won't address V, A,
polarity, AC/DC, etc.]

Some info on the web wikimedia barrel connectors.
 Here's a spreadsheet with ID, OD and center pin diameters,
along with mfr ident and typical use (user beware):
 https://ve3ute.ca/query/IEC_EIJ_DIN_Barrel_Connector.zip
 Center-pin equipped parts expect resistively programmed
info for correct function a la USB-C. Some expect to be
output-voltage-adjusted by the same means.

I thought the "three-pin" variants talked to an I2C-sortof
device *in* the brick to identify the actual device?

Note that current ratings assume correct mating and may
not be guaranteed by various mfrs or vendors.
 Labelling the installed connector can be useful if your
memory doesn't serve you well.

Once you have the mating wall-wart/brick, you typically
care little about the actual connector being used.
It's not like you're going to plug something ELSE into
that port.