Timer Circuit using IC 555


This timer circuit using IC 555 can be used as an alarm after certain time.In daily life there is many timer  circuits we may use but how about designing and implementing your own timer circuit in your home.This circuit is very simple to understand and also to implement.Lets see how it works.


The IC 555 works in Monostable multivibrator mode.Monostable mode is often called as one shot multivibrator.It is a pulse generating circuit in which the duration is determined by RC network connected external to it.Here a switch S1 is given as reset push button and when the switch was pressed the timer starts and green LED D1 glows after the end of timer(pulse generated).

Here the capacitor C1 and C2 discharges the voltage stored in it and it decides the timing of this circuit.When the trigger pulse is applied output is forced to high and it remains high until capacitor is completely discharges if you need more time you can connect high values of capacitor and resistor to it.The pot R4 can also be used to vary the time duration of your timer circuit.Instead of LED you can also use Relay or any other component based on your need.


The following two tabs change content below.
Frank Donald
Frank Donald is an Electronics and Communication Engineer who loves building stuff in his free time. Video games, blogging and programming are the things he loves most
Frank Donald

Latest posts by Frank Donald (see all)

Ask your query

2 Comment threads
0 Thread replies
Most reacted comment
Hottest comment thread
1 Comment authors
Frank Donaldaudio system Recent comment authors
newest oldest most voted
Notify of
Frank Donald

sure it does.Many modern ICs was discovered but still NE 555 holds a special place.

audio system

when i was engineering student . then in BEEE this topic is very important . this circuit play important role in electronics era .
interactive whiteboards