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L39, 7-Segment Counter

It’s the circuit diagram of a seven segment counter based on the counter IC CD 4033.This circuit can be used in conjunction with various circuits where a counter to display the progress adds some more attraction.

IC NE 555 is wired as an Astable multi-vibrator for triggering the CD 4033.For each pulse the output of CD 4033 advances one by one count. The output of CD 4033 is displayed on the seven segment LED display LT543 (Common cathode).Switch S1 is used to initiate the counting. Diode D1 prevents the risk of accidental polarity reversal.


  • IC1 = NE555, IC2 = CD4033

  • R1 = 47K, R2 = 220K, R3 = 47K,

  • R4 = 330ohm, R5 = 470 ohm

  • C1 = 0.01uf

  • D1 = 1N4007

  • 7-Segment (Common cathode)

  • S1 = Push Switch


In any case, if this circuit is not work, connect pin no.3 of IC2 with Vcc +5v and connect pin no.5 of IC1 with ground within a 0.01uf capacitor in series.

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