Here I’m introducing a simple and very useful project to store the running time of any device. The running time in minutes can be seen on a 7-segment display and can be reset at any time to it’s initial zero condition by pressing a switch. It can be easily installed by connecting it in parallel with any device. The reason to make behind this project is; one day a farmer in my area asked me that he want to keep remaind the total running time of the pump even on power failure. Then I decided to make this one and now he feel reliable to calculate the running time easily.
The project is made with a microcontroller (AT89C2051), EEPROM chip(AT24C02), common anode 7-segment display etc. Pushbutton PB1 is to refresh the system and PB2 is for reset the project to ‘0000’. The circuit requires 5V DC supply that be achieved from many of DC operated equipments. If you want to connect this project with any high voltage AC operated equipment then you need to install a step down circuit also.
Here is the breadboard arrangement.
During running condition, the mcu makes a clock program to display the minutes and stores these values on EEPROM chip. When power supply resets, the project starts from the last stored time.