... , battery backup, low power, stable and liable pcb design 1.5 inch 4 digit bus digital clock with temperature and date display Master ... environment: Temperature -10 ~ 70 , humidity from 0 to 90% 7.4 digital display, 1.5-inch high characters for the red LED display; 10 ... a cell battery for time memory when no power supply 1.5 inch 4 digit bus digital clock with temperature and date display