OT: Self installed Home Burglar Alarms?

[Microman]

A long time ago after we got burglarized I bought a Schlage Keepsafer home burglar alarm. There was a main control unit, and remote sensors that would go on the windows and doors. Still there but getting old, and not using it anymore. And I want to put it into action again, and I am sure that it is not supported any longer.

Are there any others that are available? What is the current technology like?

Thanks.