[sdiy] Jack insertion detection

[Andre Majorel]

On 2018-07-23 14:21 -0700, Tim Ressel wrote:

> I've got another challenge: how to detect when a plug is
> inserted into a jack. These are 3.5mm mono jacks btw. The
> current method is to use a stereo jack. When a mono plug is
> inserted the ring connection gets shorted to ground by the
> sleeve of the plug. This method works well, but the stereo
> jacks are taller than the mono jacks.
> 
> The only jack I can use is a switched mono jack where switched
> port is tied to the tip port until a plug is inserted. My idea
> is to use the switch port to feed an out of range voltage to
> the tip port, probably a negative voltage. Then use a
> comparator to detect when the tip port goes high.

Just in case you don't already know, there are phone jacks with
isolated switch circuits. Switchcraft 113EX and 113X, for
example :

  http://switchcraft.com/Drawings/110x-m110x_series_cd.pdf

I've seen 3.5 mm sockets with suspiciously high number of pins
so something similar may exist in that size.

-- 
André Majorel http://www.teaser.fr/~amajorel/