A small shape three port manostat of 78L05 with the output current of 150mA is added on the electrical source end, so the input voltage is decreased from 15V to 12V to supply DM74LS123N.

• 在控制电路芯片的电源端口增加一个输出电流150毫安的小型三端稳压块78L05，把12伏的输入电压降到5伏给DM74LS123N供电。