Detect Insertion of Plug Into RCA

[maczrool]

Is there a circuit I could use that would yield a high or low signal based on whether a plug is inserted into a female RCA jack? The jacks I've seen all switch across the tip which would make it difficult to pull high or low without interfering with the signal on the tip.

I'd like to be able to control a mux IC with this to select different sources based on whether the user has inserted something into the RCAs.

Thanks,
Stu

[sofaspud]

What you describe seems to be a mechanical question, and I can't think of a solution for RCA's.

[jackinnj]

On the outside you could use an optical sensor, capacitative touch sensor or impedance sensor.

[maczrool]

Thanks guys. I thought about the optical sensor but most seem to only operate at 5+ volts and I only have 3.3 available. After thinking about it, I think it will work just as well to have both outputs active at the same time and substitute the MUX for a logic buffer.

Stu

[sreten]

Hi, a logic buffer won't work, as far as I can tell, rgds, sreten.

3.5mm has tip (and earth) switching, RCA phono's don't at all.

[maczrool]

I have an I2S stream which I was routing through a MUX (on paper) to a DAC and an SPDIF transmitter. These were routed to a mini optical jack with 3.5 mm analog contacts and grounded switches for detection but I decided I wanted the circuit to use more robust connectors so I broke them out into separate RCAs and Toslink transmitter module. I'll just rout the I2S through a buffer to the DAC and transmitter IC simultaneously rather than bother trying to detect and switch the outputs. Should work well.

Stu