How create a simple on/off Animated objects ?

Hello everybody.

I would like create a Spear Wall with a simple animation Turn On/Off like the Momentum Conserver in Get to Work expansion pack.

I create the mesh. I create in the blender file the animation.


But I can't find a good tutorial or simple tutorial for to create a simple interaction on/off.
I don't want a mood or sound.
I want just on/off for beginning my animation on the object like the Momentum Conserver.
This my file if it can help you.
Spear Wall

A tutorial would be very appreciated.
I tried that of necrodog but it is very complicated and with the bug on his video it is even worse.
Could you help me please ?
Thanks