Dummy Alarm Project

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Home | Map | Projects | Construction | Soldering | Study | Components | 555 | Symbols | FAQ | Links Dummy Alarm Project A kit for this project is available from RSH Electronics . Download PDF version of this page This Dummy Alarm project makes an LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. An on/off switch is not included, but could be added if you wish. The 7555 timer IC used is a low power version of the standard 555 timer. A 'superbright' red LED is used because this provides a bright flash with a low current. The LED is off for most of the time so the average total current for the circuit is less than 0.2mA. With this very low current a set of 3 alkaline AA cells should last for several months, maybe as long as a year. The circuit will work with a standard 555 timer IC (such as the popular NE555) but this will increase the average current to about 2mA and the battery life will be much shorter. You can use
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This note was uploaded on 03/31/2012 for the course ECE 101 taught by Professor X during the Spring '12 term at Florida A&M.

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