[SENT] Continuous Usetype and hooking into cessation of usage? Also: Activator/Caller?

So I’m making a SENT Healthcharger for my gamemode, because the engine health charger doesn’t have a keyvalue for health: They always heal the same amount.

Anyway, I’m trying to make the sound play WHILE it’s being used. I have it playing just fine, but I can’t figure out how to catch when the Activator stops using the entity. Any tips, or IMPOSSIBRU?

Also: What’s the difference between the Activator and the Caller in this hook?

I think the caller has something to-do with brushbased entities in hammer, you should only care about activator though in 99% of the cases.

I figured it was something that I ought not be using.

EDIT: So I figured out how do do what I want to do (thanks VoiDeD.)

For those that want to know…

All you really have to do is defer Think in your Use function. Then, think can signify the end of use.