What is Digital Timer : Circuit Diagram and Its Working

Timers are traditional types that are classified into two type’s namely analog timer as well as the digital timer. The timer is an electronic circuit that produces periodic signals to the system which can change the state of that digital system. This timer provides accurate results than traditional clocks. This timer is a small device; in that, a timer is used with fixed time so that it will beep once set the desired time. The timer can be an additional option to reset it. There are many applications of these timers in various fields. This article discusses an overview of the digital timer and its working

What is Digital Timer?

A digital timer will display the time by default for24 hours 60 minutes and 60 seconds. This timer can display the actual time in hours and minutes and seconds whereas the traditional clock is not accurate than the digital clock. A timer is a device that shows the time in each aspect like hours, minutes and seconds too.

Working Principle

The working principle of the digital timer is, it uses the power source and different electronic components for a time like hours, minutes and seconds. The power source of this timer is either a battery otherwise a power cable connection or the clock gearing controlled by the counter. Finally, it displays the time either on LED or LCD screen.

Digital Timer Circuit Diagram

The following diagram is the schematic diagram of a digital timer and its construction can be done with the help of AT89C51 microcontroller, seven-segment display, 230V 50Hz transformer, bridge rectifier unit, LM7805CT regulator, 12MHz crystal oscillator and buzzer for alarms. These can be arranged as shown in the schematic of this timer circuit.


The power supply circuit of this timer can be designed with a transformer, bridge rectifier & LM7805 voltage regulator device. The arrangement of the power supply is shown in the below diagram.


The power sources used for this circuit are a transformer or simply a battery. For ease, a battery can be used in all digital timer devices. AT89C51 microcontroller is a low power and high-performance controller. It has the 4kB of flash PROM. It is a 40 pin IC and it has two 16 bit timer/counters, on-chip oscillator circuit. The detailed pin description of the AT89C51 is shown below.

  • The 40 pins are divided into four ports like port 0, port 1, port 2, and port 3. In those the main important pins are
  • Pin 9 for RESET. This pin is used to reset the micro controller’s internal registers
  • Pin 18 and 19 are connecting to the crystal oscillator for providing the stable oscillations to the circuit. The crystal oscillator produces the oscillations at the 11.0592 MHz frequency range.
  • Pin 40 and pin 20 are for the Vcc and ground. AT89C51 microcontroller requires a +5V supply for proper functioning.
  • Pin 29, 30 and 31 for memory purposes.
  • Pin 7 of port 3 can be connected to the buzzer for alerting the user of a particular time event.
  • This timer circuit can also be used for the purpose of timer and alarm. The buzzer device will help you to give an alert to the user. And the required power supply comes from the power supply unit.

Thus, nowadays Digital timer controller is an essential device and it has a lot of applications in all major devices. And this can be implemented by using a basic microcontroller and advanced CMOS devices also. The difference is only the circuit complexity and its features. This timer can be extended by simply placing some sensors like heartbeat sensors, GPS and tracking sensors. Here is a question for you, what are the applications of digital timer?