I still own a Halogen detector that I bought 30 years ago. It works with a propane bottle. I left it at the restaurant I used to work at and the guy owns the restaurant says he still uses it. I could never get the thing to work unless I held the flame in front of a full bottle of Freon and cracked the tap to open.
I think Benesesso you may be right.
But I still want a cute little electronics one.