DIY Security System Do I need Steping Power Supply

[ArkBigFoot]

I am making a security door system with reed type magnet switch. I have tried it on my desk and it works. I can set the time to stay on for several minutes. I was wanting one which would stay on even if they closed the door back quickly. This does that. My questions are: Do I need a stepping 12 volt power supply to power the relay? I am using a 2amp 5 volt phone power supply. Should that be larger? Are there any resisters or additional componnents I need? Can I "dasiy chain" them so more than one Reed swithch will trigger it?

 

[telectrix]

looks like you need 12V for the relay coil

 

[ArkBigFoot]

The relay has a power supply of 12 volts in and says it can handle 110 volts out which the alarm is. I am going to use a cellphone activated plug (WeMO) which will allow me to turn the power on/off to the 5 volt power supply as I leave and return. I will install inside a closet near the WiFi network because I am not sure if the circuit board can handle the hot temp in the attic during the summer. I have 3 doors. Can I dasiy chain them or will I have a current loss which will not activate the relay? These could be as far away as 40 feet from the door reed switch to the main circuit board.

 

[ScottPiligrimm]

Guys, I'm not so good at circuitry. Is it hard to do it on my own?