4 Digit Up/Down Counter Circuit Тўрт разрядли олдинга/орқага сановчи санагичнинг структуравий ва принципиал схемаларини қуриш

Triggering The Counter
Synchronous Counters use edge-triggered flip-flops that change states on either the “positive-edge” (rising edge) or the “negative-edge” (falling edge) of the clock pulse on the control input resulting in one single count when the clock input changes state.
Generally, synchronous counters count on the rising-edge which is the low to high transition of the clock signal and asynchronous ripple counters count on the falling-edge which is the high to low transition of the clock signal.

It may seem unusual that ripple counters use the falling-edge of the clock cycle to change state, but this makes it easier to link counters together because the most significant bit (MSB) of one counter can drive the clock input of the next.
This works because the next bit must change state when the previous bit changes from high to low – the point at which a carry must occur to the next bit. Synchronous counters usually have a carry-out and a carry-in pin for linking counters together without introducing any propagation delays.
Tutorial Summary
Then to summarise some of the main points about Synchronous Counters:

• 
  Synchronous Counters can be made from Toggle or D-type flip-flops.
  
• 
  Synchronous counters are easier to design than asynchronous counters.
  
• 
  They are called synchronous counters because the clock input of the flip-flops
  are all clocked together at the same time with the same clock signal.
  
• 
  Due to this common clock pulse all output states switch or change simultaneously.
  
• 
  With all clock inputs wired together there is no inherent propagation delay.
  
• 
  Synchronous counters are sometimes called parallel counters as the clock is fed in parallel to all flip-flops.
  
• 
  The inherent memory circuit keeps track of the counters present state.
  
• 
  The count sequence is controlled using logic gates.
  
• 
  Overall faster operation may be achieved compared to Asynchronous counters.
  

In the next tutorial about Counters we will look at bi-directional counters which are able to count in both an upward direct and a downward direction.