Price: $14.99
(as of Apr 30, 2024 14:55:27 UTC – Details)
60-binary circuit principle of operation: when the time is 60 seconds, the 4518’s ten-bit output of the BCD code is 0110, through a with the gate circuit (CD4581)
connected to the 4518’s Q2B and Q3B terminals, when up to 60 seconds, these two terminals at the same time, the output of 1, through the output of 1 with the gate
circuit to the CD4518 to clear, the number of re-counting from 00, and at the same time, to give a sub-signal or time At the same time, a pulse plus 1 is given to the
minute signal or time signal.
The 24-binary circuit works similarly to the 60-binary circuit, except that the signal taken is 24. The BCD code output from the 4518 is 0010 0100, which can be
taken from the Q2B and Q3A terminals of the 4518. The circuit does not have a power failure memory time function, you need to re-calibrate the time after power failure.
Circuit Installation and Commissioning.
Solder in the order of the component list, install the short component first then the tall component.
Integrated circuits are soldered The IC holders first, chips are mounted on the socket last.
Components that do not distinguish between pin direction: resistors, crystals, ceramic capacitors, toggle switches.
Components with positive and negative poles:Light-emitting diodes and electrolytic capacitors with long pin are positive, aligned with the position marked + on the board,
and the position of 1N4148 with a black circle is aligned with the position of the white mark on the board.
The notch position of the IC holder is aligned with the direction of the notch position on the circuit board, and the notch position of the IC is also aligned with the notch mark on the circuit board.
The flick switch can be loaded normally in the correct position.
Pin order identification: chip text is aligned with their own, from the lower left corner of the first foot is 1 counterclockwise number.
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.
