Ok, I took on a weird project for my boss and not sure how to do it, I need a pressure plate switch to set off a siren but only for about 3 seconds and have the option to make it so I need to reset it before it can trigger again or have it set to go off each time the switch is activated. How do I do this to have the time limit and the settings options?

 

A monostable multivibrator, aka "one shot", can behave that way. This is a standard use of the 555 timer IC. You would use its output - a 3 second "on" pulse, to control power to the siren which is assumed to make noise on its own once powered. If it needs more than 200mA, you can use an external MOSFET switch to control a current as large as you need.

 

Found it, I am a beginner, I am not clear on how to make it.

 

Found it, I am a beginner, I am not clear on how to make it.

First you’ll need a source of DC power. Whatever you were planning to use for the siren will probably work. Does your siren make noise with just DC power? How much current (amps) does it require?