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LED Digital Counter
Counting chips can drive a display directly.
LED SYMBOLTriangle points from anode to cathode; the arrows show light leaving the part.
Counting with chips
Counter chips such as the 74HC4026 count pulses and drive a seven-segment display directly. Cascading chips gives tens, hundreds and more.
Building one
- Feed pulses from a debounced push button.
- Link each chip's carry output to the next chip's clock input.
- Add a reset button to return all digits to zero.
A microcontroller does the same with a number variable and multiplexed display, making wrap-around, up-down and preset counts easy.
REMEMBER
Debounce the input or one press may count twice.Try it yourself
Sketch the circuit on paper first, calculate the values, then build it on a solderless breadboard using a low-voltage supply. Measure with a multimeter before you make anything permanent.
Explore LED clocks, stopwatches and electronics at cosycom.com.