Breadboard View

images/timerAlarm_bbW.png

Although in this example all the trigger switches are on this breadboard, in real life you may have to run wires to place the switches where they will be triggered.

First, build a small breadboard of the circuit, so you can see what is happening before you set up a DIY security silent alarm. The three momentary contact switches on the right half of the board are actually three separate triggers for the alarm. You could simply remove them and use long wires to place a contact switch anywhere you want to monitor.

images/p20_timerAlarm_25.png

Connect the negative ...

Get Essential 555 IC now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.