As shown, in FIG a decimal seven storage - Decoding - drive unit 74 143, this unit has a constant output for all segments. Each at a voltage of 5V when the current is about 15
~ 22mA. Seven segment decoder BCD data can be removed from the 17 to 20 feet. 22 feet for a carry, that is, when the count value to 9 after the low, remaining high. Using this signal can control a counter. Figure b for controlling one or 1 1/2 digit seven-segment LED display circuit. SAB3211 as 4-bit binary counting. It may be needed before the next binary counter (FZJ151) or decimal counter (FZJ141). Supply voltage 9 ~ 16V.