But there have been many times where I know sex is about to happen elsewhere and I'd like to leave a recorder there. I would never leave my phone unattended but if I did there's ultimate privacy as nobody would know anything is going on.
My phone solves two problems.
1, there's no flashing lights or notification indicating something is being recorded.
2, if they try to hook up the phone to their computer, they'll find it's encrypted and can't get anything off it.
So ultimate privacy!
What types of recorders would give that same level of privacy if found by someone? I've been looking up the USB recorders that many people mention here. It does solve the first problem, that someone who just sees it laying around won't know it's recording anything because it looks like a USB drive (and shouldn't have flashing lights if you choose the right one). But the second problem is still there, if they put the USB drive into their computer they'll realize there are recordings on it. (I know the odds are low of them doing that but it still concerns me.)
That's fine for if you're leaving it in a public place like a hotel corridor where if someone picks it up and discovers it's a recorder they won't know who left it there. But in other cases, like the corridor of your own home, they'll know that it was you.
I don't know if there's any kind of USB drives or other recorders that are encrypted or password-protected, or need some kind of physical key or whatever to hook up to the computer to get the files from it.
But unless I can find something like this I don't think I'll be able to do much recording.
And I'm in a situation where I can really get some great ones, so I hope you have some good advice for me! 
