A cheap and practical quick checker for Chinese zodiac signs

This circuit is shown in the figure below. The working principle is as follows: IC1-1C3 are three decimal counting frequency dividers CD4017. IC1 and light-emitting diodes LED1~LED10 form the ten-digit display circuit of the Heavenly Stems; IC2, IC3 and LED11~LED22 form the twelve-digit display circuit of the Earthly Branches. IC7 and IC8 are two decimal reversible counting and decoding driver integrated circuits. Together with the common cathode digital tubes IC5 and IC6, they form the year display circuit. Since the year and the zodiac signs are synchronized, LED1~LED10 and LED11~LED12 and IC5 and IC6 are driven by the counting pulses output by the pulse oscillator composed of NOT gates F1 and F2, and are displayed synchronously. F1~F6 are six NOT gates in a six-NOT gate integrated circuit.

The power switch K also serves as the total reset switch. When K is just closed, the spike pulse generated by the differential circuit of R9 and Cl acts on the Cr terminal of IC1~lC3 at the same time, and IC1-lC3 is cleared at the same time. The spike pulse generated by the differential of R5, C3 and R6, 04 acts on the Cr terminal of IC7 and IC8 at the same time, and IC7 and IC8 are also cleared at the same time. At this time, the QO terminal of IC1 and IC2 outputs a high level, the light-emitting diodes LED1 and LED11 emit light, and IC5 and IC6 display 00, indicating 1900, the year of Gengzi, and the zodiac rat. (Note: 00 does not mean 2000) When the quick query button AN1 is pressed, the counting pulses generated by the F1 and F2 oscillators are added to IC1 through F3~F5 respectively. IC3 and IC7 are the addition counting input terminals. IC1 and IC2 take turns to output high level from Q0 to Q9. LED1~LED10 and LED11~LED12 take turns to light up. The years displayed by IC5 and IC6 increase year by year. Here, IC2 and IC3 form a duodecimal counter. Its working process is as follows: At the beginning, the EN terminal of IC2 and the Q9 terminal are connected to a low level, IC2 is not allowed to count, the non-gate F6 outputs a high level, and IC3 is prohibited from counting because EN is a high level. When Q1 to Q9 of IC2 take turns to be high level until Q9 is high level, Li also becomes high level, counting is prohibited, and F6 output becomes low level, IC3 starts counting, Q1 becomes high level, and when it is the turn of Q4 of IC3 to be high level, the high level clears IC2 and IC3 at the same time through D2, and Qo of IC2 becomes high level, and the duodecimal counter starts counting for the next cycle.

During the counting process of IC1~lC3, IC7, and IC8, when the numbers displayed by IC5 and IC6 reach the desired year, release AN1, and the corresponding heavenly stems displayed in LED1~LED10 and earthly branches displayed in LED11~LED22 will indicate the corresponding relationship between the heavenly stems and earthly branches and the zodiac sign of that year. For example, in 1970, LED1 lights up to indicate that the heavenly stem of that year is Geng; LED21 lights up to indicate that the earthly branch of that year is Xu; and the zodiac sign is Dog.

When IC5 and IC6 display 99, and a positive pulse is input from the CPU end of IC8, lC5 and IC6 return to 00. At the same time, the carry end CO of IC5 outputs a positive pulse, which clears IC1~lC3 at the same time through D3. All counters start counting from 1900 again. Therefore, no matter how long AN1 is pressed, the displayed thousand, zodiac, and year are all correct.

In the figure, D1 to D3 are all isolation diodes to prevent the mutual interference of irrelevant reset pulses. AN2 is a slow check button. When AN1 is pressed, the digital tube numbers increase rapidly. When it is close to the year to be checked, AN1 can be released and AN2 can be used instead. Each time AN2 is pressed, a low level is input to the F3~F5 input terminal, a high level pulse is output, and the counter increases by 1. This can prevent "overrunning".

Component selection: IC1-IC3 use decimal counting divider CD4017 (or MC14017). IC4 uses a six-not-gate digital integrated circuit CD4069. IC7 and IC8 use two decimal addition and subtraction counting decoding drivers CD40110, and only the addition function is used here.

IC5 and IC6 use two common cathode digital tubes LC5011. The power supply of the whole device can be completed by connecting dry batteries in series. If it is used frequently, it can also be powered by a power transformer above 8VA to reduce the voltage, rectify and filter to obtain a DC voltage of about 12V. LED1 to LED10 can be red, and LED11 to LED22 can be green high-brightness light-emitting diodes.

Production: Except IC5 and IC6, all other integrated circuits are installed with IC sockets to ensure the safety of CMOS devices. All components except K, AN1, and AN2 are installed on a circuit board and placed in a plastic box. The box cover can be made of a transparent organic glass plate, so that the ends of LED1 to LED22 just support the box cover, and the words "甲乙丙丁戊己庚辛壬癸", "子丑寅卯辰巳午未申酉戌亥", "牛鼠猪狗鸡猴羊马蛇龙兔虎" are written on the corresponding positions of the light-emitting tubes with paint. K, AN1, and AN2 are installed on the edge of the box cover.

This circuit has no adjustable components. If the speed is too fast or too slow, just increase or decrease the resistance of R2 appropriately.