Setting Sleep Time For External HD

[neocell]

Sorry if this has been covered before (having problems with the search function) but is there a way I can set when (after how long) my external HD goes to sleep. Right now it spins down after about 5 minutes. It's just a bit of a pain when I got to the contextual menus of files as the computer freezes until the external spins up. If anyone knows of a way to do this with OSX or with a 3rd party app I'd appreciate it.
Thanks a lot

 

[Eraserhead]

See this.

and disable sleep hard disks when possible.
(You may need to unlock your preferences first as I haven't in the screenshot)

 

[neocell]

Yeah, but that's only for the internal one(s). Doesn't do anything to my external sleep time

**EDIT**
My bad. I went back to check the system preferences to make sure it was off and it wasn't (I originally turned it off when trying to resolve this issue about 6 months ago, must have forgotten and turned it back on or with a system upgrade...) and now that I've turned it off it appears to be working. Thanks Eraserhead and sorry for the bad thread.