Position: Index > Led Circuit >

Dummy Alarm with Flashing LED

2014-12-11 05:32  
Declaration:We aim to transmit more information by carrying articles . We will delete it soon, if we are involved in the problems of article content ,copyright or other problems.
Figure:1

Figure 1 

ALEDflashing briefly once every 5 seconds to imitate the indicator of a real alarm is the function of this dummy alarm project with the use of a 7555 timer IC.

To prolong battery life, the circuit was designed to use very little current in order to be left ON permanently. Optionally, an ON/OFF switch may be included if desired. The circuit uses a low power version of the standard 555 timer, the 7555 timer IC. A bright flash with a low current is provided by a super bright redLED. The average total current for the circuit is less than 0.2mA since theLEDisOFFfor most of the time. A set of 3 alkaline AA cells should last for several months or a year with this very low current.

A standard 555 timer IC can also be used in the circuit which will increase the average current to about 2mA while the battery life will be much shorter. If a greater power supply voltage at 15V maximum is used in this alarm, the 1K resistor for theLEDshould be increased to keep theLEDcurrent low around 3mA.

Click here to see the rest of the project.


Reprinted Url Of This Article:
http://www.circuit-projects.com/alarm/dummy-alarm-with-flashing-led.html