I have a simple security/alarm system I built for my carport after a thief took advantage of me. It simply has a strobe light and an extremely loud siren, using photoelectric sensors. When the sensors are tripped, the strobe and siren sound/light up. What I want to do is turn the system off after about 5 minutes once tripped, then be able to engage itself again if need be. Any suggestions on a simple timer? This is a low voltage dc system.
Follow these instructions :
Change variable resistor( number 1 ) to 1 Mega-Ohm It gives you 5 minuts ON-State then on delay and then it goes to OFF/State (in this state it will be ready for another trigger).
Your trigger is number 2 : You can use a transistor instead of push button key. Connect emitter and collector of your transistor instead of push-button's pins and you have to connect your command signal line to the base of this added transistor (i didn't about your output signal's voltage and i didn't design this part for you bur it's so easy and i think you can do it by yourself).
Connect a suitable relay instead of marked LED & resistor ( remember, you have to connect a common diode to your relay's coil in parallel but in inverse bias, it prevents fly-back surge voltage damage to you transistor and you must install it)
If something in this post wasn't clear for you, talk about it, i will explain more