[sdiy] "Mini-jack" myths

[Cary Roberts]

>As you mention, 1/4" jacks have their origins in telephony dating back to
>probably early 20th century (If not before).

1/4" plugs showed up around 1880 where they were first used in switchboards.
The TRS variant likely appeared within a decade as patents for such were
filed in 1894.  I'm amazed the TRS variant was able to be volume
manufactured and they must have been quite pricey.  AC plugs from the same
era are crude by comparison.

>I believe the 2.5mm and 3.5mm jacks have their origins in Japanese
transistor
>radios used for earpieces or "record out" connections. This is where I
first
>encountered them.

While the size might have originated in Japan, the actual shape of the plug
and tip are depicted in patents from the 1920s and 30s.  So I find it funny
the tip shape is referred to as "Japanese" style.

>I think the Switchcraft Bantam TT plugs are an odd one unique to
>them.

Bantam (also known as tiny telephone) jacks provide twice the density of
standard 1/4" jack frames.  They were specifically designed for test access
in telcommunication circuits.  It's no coincidence the Switchcraft is
headquartered in Chicago where Western Electric had a sizable manufacturing
facility.

-Cary