Anti-shutdown device circuit using electronic counter as counter

When using an electronic calculator as a counter, the actual counting pulses are not always continuous. If the interval between two pulses exceeds the calculator
's automatic delay shutdown time (generally electronic calculators have this function), the calculator will automatically shut down and the numbers will be disappear.
In order to prevent automatic shutdown, an anti-shutdown device needs to be installed, as shown in Figure 15-64. It is actually a delay circuit. Lead two wires from
both ends of the "CE" key of the calculator and connect them to the normally open contact of the relay KA. The main function of the hole reader is to convert the program signal
(the presence or absence of holes) on the perforated tape into the corresponding electrical signal .