Home Alarm System

[oxygen454]

I have searched all through this forum and all through the net but I am unable to find much information on how to build a simple alarm. I need a schematic to build the circuit. I dont have a way to program ic's so I just want to use the good old chips. I build an alarm in high school but I lost the schmatics for it. Is there a 555 involved?

I want to build an alarm that triggers when a door is open and delays for a certain amount of time (30 sec.) and then triggers a siren. All running 12 vdc.

Any help would be much appriciated!

Chris

 

[Russlk]

My website has a schematic of an auto alarm, which would be applicable. You will have to copy and paste the URL into the address bar, because geocities does not allow links.

 

[oxygen454]

hey I think that might just help thanks! It looks pretty confusing and will ahve to break it down so it will work for a door trigger in a house or in this case for our shed.

To all the rest interested I just found a siren circuit that I am going to try. Found at: **broken link removed**

Thanks Russlk! If anyone has any more simpilar diagram or has ideas please help out! haha

Chris

 

[niq_ro]

see at my website: **broken link removed** and **broken link removed**
language is roumanian, but I think undestund the schematics

 

[oxygen454]

Okay simplifying the circuit a bit. I have a siren from a car alarm system that will be triggered when the door is opened with out the right code. What I need to figure out is how to make a circuit so that when a door is opened it knows and triggers on the siren.

When the right code is entered it will send an approx 3 second pulse to a transistor which in turn will the power off to the sensor on the doors. So far only have the key pad somewhat worked out.

 

[oxygen454]

Better reword my question. How can I make a simple circuit with say transistors or whatever needed to build my alarm. I have the keypad and siren but what i need is to make a device so that when the door is closed a light shows armed and ready, then when the door is opended, it triggers a open state in the line and sets off the siren.

I need simple as it gets because I am not too advanced with electronis. I know somewhat about ic's and the basics of grade 12 advanced electronics haha.

You guys are always a huge help! Keep up the great work!!