This Adjustable Timer Circuit using 555 IC with Buzzer shows how to make one timer circuit and this timer can change time and make sound with buzzer using IC 555.
Timer is like small clock for electronics.
Timer can turn things ON and OFF after some time.
We see timer in many things like microwave and traffic lights.
There are two types of timer.
One type is inside a machine like hardware, another type is using program like software.
In this project we have used special chip called 555 timer and with this chip we can make timer that can give alert like sound when time is up.
The article explain how this circuit works step by step and also show small science with formula and give help how we can start our own timer project.
Circuit Design and Formulas:
Main part of our timer circuit is 555 timer chip IC1 we have used it in monostable mode which gives us correct time delay.
Circuit also have one variable resistor and with this we can change how long the timer stays ON.
Buzzer gives sound when time is over.
Other parts help circuit work good and stable.
IC1 works in monostable mode and it is main timing part of circuit.
We can change timer time using this formula:
T = 1.1 × R × C
where:
- T is how long the timer stays ON in pulse time
- R is resistance of variable resistor is potentiometer
- C is the capacitor value
Buzzer is important part in the circuit and it gives beep sound when time is finished.
Capacitor C1 works together with variable resistor and they decide how long the timer works.
Resistor R2 is between 555 timer and buzzer it controls how much current goes to buzzer.
We have used ohms law for the following formula:
V = I × R
where:
- V is voltage across resistor
- I is current
- R is resistance
Circuit Diagram:
Parts List:
| Components | Value | Qty |
| Resistors | 9.1k and 20Ω 1/4 watt | 1 each |
| Variable Resistor potentiometer 1M | 1 | |
| Capacitors | 1000µF 25V | 1 |
| Semiconductors | IC 555 | |
| Buzzer 9V | 1 | |
| Push-button switch | 1 | |
| 9V Battery | 1 |
Circuit Operation:
Circuit start with 555 timer IC in monostable mode it does not get power first because switch is off and the switch is connected to pin 2 trigger pin.
When we press the switch it gives negative signal to pin 2 and this starts the IC.
At same time variable resistor and capacitor we call them timer parts are connected to power and pin 6 threshold.
They help to decide how long timer works.
Output pin of IC pin 3 connects to buzzer through resistor R2.
Positive side of power is connected to pin 1 of IC and negative side connects to pin 8 which also connects to pin 4.
When we give input to circuit then timer makes one pulse.
Time of this pulse depends on values of resistor and capacitor by using the formula:
T = 1.1 × R × C
If we change the variable resistor we can change time.
Timer delay can be short like 1 minute or long like 10 minutes.
Applications:
We use timer in many things in daily life.
Timer help control time in correct way.
They check that machines work safe and proper like washing machines.
Also timers are used in printers to control pumps and coolers in factories and to manage traffic lights timing on roads.
Conclusion
To conclude the Adjustable Timer Circuit using 555 IC with Buzzer are in monostable mode gives easy and good solution for many uses at home and in business where we need exact time and alert sound.
It is helpful in electronics because it is simple, easy to change time and uses some basic formulas to work.