[sdiy] Jack insertion detection

[rsdio at audiobanshee.com]

For 1/4” jacks, I believe that the sleeve is normalled to an extra pin. That pin is used to detect a jack insertion. With no jack, the extra pin is grounded. With a jack, the extra pin has something like a pull-up resistor that allows a binary detection. No need for weird noise signals or other complexity.

For 1/8” jacks, I’ve only used ones with normalled pins for the tip and ring. I don’t know of any with normalled sleeve pins. If you could find one with normalled sleeve pins, that would be ideal.

Brian


On Jul 23, 2018, at 2:21 PM, Tim Ressel <timr at circuitabbey.com> wrote:
> Hello supremely helpful folks!
> 
> 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.
> 
> Any other thoughts?