40 September 2013
BUILD IT YOURSELF
BUILD THIS SIMPLE ALARM
SYSTEM WITH THE
By Derek Tombrello Go to www.nutsvolts.com/index.php?/magazine/article/ september2013_Tombrello for any additional files and/or
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Years ago, I designed a very simple alarm system for my shop that was armed
and disarmed with a barrel key. The only components (aside from the door sensors
and the siren itself) were a relay, a transistor, and a key switch. While that worked
great, I had originally intended to (eventually) add a keypad interface, but never got
around to it. Now, with Texas Instruments' low cost ultra-low-power MSP430
microprocessor, there was no reason to put it off any longer!