anyone know how John Pearse piezo 'bug' pickups work?

[pondweed]

I've got this which I'm trying to test. Having bought a 2.5mm jackplug converter and tested that has continuity, it doesnt produced any output on a small amp, going via 2.5 to 3.5 to 1/4" into the amp.
I cannot see a way of opening it, but it has a volume control so I'm wondering whether there is a battery inside to replace too.
Any thoughts?
Ignore the other piezo - just comparing the sound return from various parts of the top. Quite interesting (but ultimately fruitless as I'll only be able to place them in one place unless I remove the top!!) HOPEFULLY I'd like to continue to use the existing "heritage" part...

 

[pondweed]

I find it is a MONO jack supplied. Jiggling the Stereo 2.5mm jack makes it occasionally work. Volume control works. So 99% there. Just need to sort different adapter. Others may benefit from info in future years....

 

[Neil_O]

Are you trying to avoid using a 1/4" cable for some reason?

 

[pondweed]

Are you trying to avoid using a 1/4" cable for some reason?

it's an old 2.5mm female output. So I have to convert to get to 1/4".... and figuring that better to have the 3.5mm lead from uke to floor as its lighter, if this pickup is to be used.