The instructions on four digital clock:

The clock will display 12:59 when it is electrified,two alarm clock will be opened by default and the first alarm clock set at 13:01,the second alarm clock set at 13:02.

Short press S2 can switch the timing interface between hour-minute and minute-second after it is electrified;long press S1 enter the system setting menu which have 9 submenus(A,B,C,D,E,F,G,H,I),submenu will transform between A to I when short press S1 and will turn back to the timing interface in the end.

A Submenu / Correction for hours / Press S2 plus one,after adjusted,short press S1 save and exit this submenu,at the same time enter B submenu
B Submenu / Correction for minutes / Press S2 plus one,after adjusted,short press S1 save and exit this submenu,at the same time enter C submenu
C Submenu / Hourly chime switch / The default state is ON(8:00~20:00),Press S2 can switch between ON and OFF(turn off the hourly chime switch),after adjusted,short press S1 save and exit this submenu,at the same time enter C submenu
D Submenu / The first alarm switch / The default state is ON,Press S2 can switch between ON and OFF(turn off the first alarm switch).If set to ON,short press S1 save and exit this submenu,at the same time enter E submenu;If set to OFF,short press S1 save and exit this submenu,at the same time enter G submenu
E Submenu / Set the hour of the first alarm / Press S2 plus one,after adjusted,short press S1 save and exit this submenu,at the same time enter F submenu
F Submenu / Set the minute of the first alarm / Press S2 plus one,after adjusted,short press S1 save and exit this submenu,at the same time enter G submenu
G Submenu / The second alarm switch / The default state is ON,Press S2 can switch between ON and OFF(turn off the second alarm switch).If set to ON,short press S1 save and exit this submenu,at the same time enter H submenu;If set to OFF,short press S1 save and exit this submenu,at the same time turn back to the timing interface
H Submenu / Set the minute of the second alarm / Press S2 plus one,after adjusted,short press S1 save and exit this submenu,at the same time enter I submenu
I Submenu / Set the minute of the second alarm / Press S2 plus one,after adjusted,short press S1 save and exit this submenu,at the same time turn back to the timing interface

Second correction: short press S2 enter minute-second timing interface,long press S2 can make second return to 0,after returning second to 0,short press S2 twice to check whether second is on time.

Attention: PR1 Resisters Packs has direction,a sense of words in the direction of the single chip microcomputer.Please note that during installation!

Four digital clock component list and schematic diagram and a description

NO. / Name / Type/specification / Serial number / NO. / Name / Type/specification / Serial number
01 / resistance / 10K / R1 / 10 / Tact switch / 6*6 / S1
02 / 10K / R2 / 11 / 6*6 / S2
03 / capacitance / 30P / C2 / 12 / IC socket / 20PIN / U1
04 / 30P / C3 / 13 / SCM / AT89C2051 / U1
05 / 104P / C4 / 14 / Buzzer / 5V active / LS1
06 / 10uF / C1 / 15 / Nixie tube / Four bits (red) / DS1
07 / Resisters Packs / 1K / PR1 / 16 / binding post / 2 core / J1
08 / crystaloscillator / 12MHz / Y1 / 17 / PCB board / 52*42mm / 1
09 / triode / 8550 / Q1 / 18 / instructions / 1