Creating a switch
From Valve Developer Community
This tutorial will show you how to create a switch that when pushed will go in and tick for a certain amount of time, then pop back out.
Entity creation
1. Using the Entity Tool, place a prop_dynamic where you would like the switch model. Set the properties to the following:
Property Name Value World Model models/props/switch001.mdl Name switch_model
2. Create a 16x16x16 block brush covering the button on the model textured with tools/toolsinvisible. Tie it to a func_button. Under Flags, check Don't move and change the Delay before Reset to however long you want to prevent the player from activating it again.
Note: For doors, make sure you give it enough time for the door to open, stay open and close.3. Create 3 ambient_generic entities near the switch. Give them the following properties:
Property Name Value Name switch_sound_up Sound Name Portal.button_up SourceEntityName switch_model
Property Name Value Name switch_sound_down Sound Name Portal.button_down SourceEntityName switch_model
Property Name Value Name switch_sound_tick Sound Name Portal.room1_TickTock SourceEntityName switch_model
For the switch_sound_tick entity, un-check Starts Silent under Flags.
4. Next create a logic_timer somewhere near the switch. Give it the following properties:
Property Name Value Name switch_sound_tickloop Starts Disabled Yes Refire Interval 1
And the following Output:
My Output Target Entity Target Input Parameter Delay Only Once 
OnTimer switch_sound_tick PlaySound <none> 0.00 No
5. Select the func_button and add the following outputs:
My Output Target Entity Target Input Parameter Delay Only Once OnOut switch_model SetAnimation up 0.00 No OnOut switch_sound_tickloop Disable <none> 0.00 No OnOut switch_sound_up PlaySound <none> 0.00 No OnPressed switch_model SetAnimation down 0.00 No OnPressed switch_sound_tickloop Enable <none> 0.00 No OnPressed switch_sound_down PlaySound <none> 0.00 No
Note: The time you have for Delay before Reset will be how long it takes for the OnOut outputs to trigger. Make sure you have it timed accordingly!
Add in your door open triggers with OnPressed and closing triggers with OnOut. You can also put in some indicator lights for added effect. Download the tutorial map here (http://www.remmiz.com/portal/maps/switchtutorial.zip).
