Description
Accurate time: This circuit uses a quartz crystal as the time base pulse oscillator, and obtains the second time base signal through digital frequency division. The time is then displayed through a counter, decoder and display. Since the crystal is used as the time base pulse, the timekeeping time is accurate..Seconds Signal Generator: Composed of CD4060 and CD4013, it generates and time reference signal with a frequency of 1 Hz. CD4060 is a 14-stage binary counter/frequency divider/oscillator. It is composed of 32768Hz oscillator with external resistor, capacitor and quartz crystal, and 14-level binary frequency divider, and then an additional level of D flip-flop (CD4013) binary frequency divider, outputting 1Hz time base second signal..Seconds, minutes, hours counter circuit :used double BCD synchronous plus counter CD4518 counting output BCD code, through the CD4511 will be the BCD code to display the corresponding figures, seconds, minutes counter is 60 decimal counting, hours is 24 decimal counting..CD4511 decoder drive digital tube: seconds calibration using the waiting calibration method, switch S3 up toggle, normal time. S3 dialled down to "stop", when the standard time arrives, it will be dialled up immediately to restore normal time. The minutes and hours are calibrated by directly inputting pulse signals through the switch, and each time the switch is pressed, a number of times is added..widely used in schools to help students learn basic mechanical and electronic skills.Through the analysis of the circuit, understand the working principle of the circuit, learn to train electronic skills, welding training.
