Clocks are important companion of our daily life. They say, “Time and tide waits for none”. So, clocks play a vital role in our progressive routine. Wrist watches, table clocks are not the only devices available to display time, there are multiple ways to do so. The project discussed here draws the layout to build an electronic clock which provides all features like a normal clock does. Fascinating fact about this circuit is that it can be operated either from the AC power line, or from an automobile, boat or plane battery.
Depending on the application, it can receive inputs from a 3.58 MHz color TV crystal or a 60 Hz power line. After being received, these signals are then counted to generate minutes, ten minutes, and hour displays. IC makes 3.75 Hz signal for flashing specific numerals or messages. LEDs or fluorescent numeral indicators are connected to the IC by separate leads extended from the segment drivers of IC. Only three control inputs are required for this circuit. To make changes to the time set on the clock, the circuit offers the ‘increment’ input which allows the user to select any particular digit from hours, tens of minutes, or simply run the clock run. Once the desired state is selected, the digit can be incremented by providing one impulse or pushbutton closing for each advance in the selected digit. The “reset” input automatically resets the clock to indicate the state 1:00.
Basic key parameters used in this circuit are briefed in points below:
- Power supply voltage: – Nominal voltage of 5 V is typical.
- Logic control levels: –
For logic 1, 2.0 to 5.0 V is a typical range.
For logic 0, a typical range would be 0 to 0.3 V
- Maximum power dissipation: – With all segments illuminated, approximately 500 mW will be required.
This IC is employed in electronic clocks of all kinds.