"Devices"

[M11k4]

Ok guys I need some help creating a device/mechanism. In Lynx, I need a trap that doesn't allow a monster passing over it to go any faster than if there was no trap. (Usually trap sliding causes open traps to work like ice.) The difficulty is the precise timing I need, and the trap needs to be closed at times, but be opened either with monster or a block (the difference being that a monster will pass over the button but a block will keep it open all the time). So I'm thinking that the trap button I have access to (with the monster or block) opens up a device/mechanism off-screen that regulates how long the primary trap is open. I've tried a few possiblities but there's always something that's not quite as I'd like it. Also, I can't use toggles or tanks, as they are used elsewhere in the level.

Any ideas are welcome, even if they don't work perfectly.