555 timer ic

On/Off Delay Timer Circuit using 555 Timer IC

On/Off Delay Timer

What is an On/Off Delay Timer?

Delay timer (on/off) Circuits are simple electronic circuits that can turn a circuit ON or OFF after a set amount of time has passed. In electrical and electronic engineering, timers are primarily employed to provide regulated delays in-circuit activities. Timers are divided into three categories. The Delay timer is on, the delay timer is off, and star-delta timer is on. In today’s lesson, we’ll go through how to make an On/Off Delay Timer Circuit with the NE555 precision Timer IC step by step.

555 Timer IC

The NE555 is a precision timing circuit that can generate precise time delays or oscillation. There are three fundamental modes of operation for the NE555. The timed interval is controlled by a single external resistor and capacitor network in the time delay or mono-stable mode of operation. The output can be designed to latch on a certain voltage level for an extended period of time in Bi-stable mode, and the IC can be reset to zero states. With two external resistors and a single external capacitor, the frequency and duty cycle can be regulated individually in an a-stable mode of operation.

The NE555 timer is used as a monostable multivibrator in this example. The duration of the pulse is determined by the R-C network, which is connected externally to the 555 timers in a monostable multivibrator (MMV), also known as a one-shot multivibrator. One output state is steady, while the other is quasi-stable in such a vibrator (unstable). Energy is stored by an externally connected capaci­tor to a reference level for auto-triggering of output from a quasi-stable state to a stable state. The pulse width is determined by the amount of time spent in storage.


Hardware Component

You will need the following parts to build this project

1)Timer ICNE5551
2)LED5mm, 3.5V1
3)Capacitor10uF, 100nF2
6)Soldering Iron45W – 65W1
7)Soldering Wire with Flux1
8)DC Battery9V1
9)Battery Clip1
11)Jumper WiresAs per need

NE555 Pinout

Useful Steps

1) Solder the NE555 time IC on the Veroboard


2) After that, solder a 10K resistor between pin 6 of the IC and the 10K pot. After that, solder a 10K pot between pin 7 of the IC and the 10K pot.


3) After that, solder another 10K resistor with pin 7, 4, and 8 of the IC.


4) Short pin 2 and pin 6 of the IC.


5) After that, solder a 100nF capacitor between pin 5 and pin 1 of the IC.


6) After that, solder the +ve pin of the 10uF capacitor with pin 6 of the IC and -ve pin with pin 1 of the 555 timer IC.


7) Solder the -ve pin of the LED with pin 3 of the timer IC and +ve pin with pin 4 and 8 of the IC.


8) After that, solder the -ve pin of the battery clip with pin 1 of the IC and +ve pin with pin 8 of the IC.


9) Power up and test the circuit using a 9V Battery.


Working Explanation

This circuit’s operation is actually quite simple. The NE555 timer is set to monostable multivibrator mode in this example. We can set the ON/OFF time of the circuit by adjusting the preset 10K pot to the desired resistance value. This will allow us to set the 555 timer’s trigger duration and threshold voltage.

When the circuit is turned on, the RC constant assigns a fixed value to the 555 timer’s trigger pin. The 555 timer either stops or opens the output to the indicator LED when the timer’s trigger value is much above the threshold.


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