Objective:
Create Asynchronous Counters, with D Flip Flops and with JK Flip Flops. After creating an up counter with each, then modify the circuit so that it counts down. The count is from 0-7.
3 Bit UP Counter with D Flip Flops
For starters, the preset and clear are wired to VCC, and D is wired to Q'. To make this an up counter, you have to connect Q' to the Clock of the next flip flop. This creates a divide by two circuit. The outputs of each flip flop is then wired to a probe which is wired to a HEX display. The HEX display then shows then numbers that result from the combination of the outputs from the flip flop.
3 Bit Down Counter with D Flip Flops
To create a Down counter from 7-0 with D Flip Flops i simply connected Q to the clock and Q' to D.
3 Bit UP Counter with JK Flip Flops
With the JK Flip flops Present, Clear, J and K are all wired to VCC. A Clock pulse is wired to the clock for the flip flops to go on. Q is wired the clock of the next flip flops. Because J and K are wired to VCC, they will change every time. The outputs are connected to the HEX display to see the number count.
3 Bit Down Counter with JK Flip Flops
To make the JK Flip Flop Up Counter, into a Down counter you simply connect Q' to the CLK. As Shown in the picture below.
The Ripple Effect
What is the Ripple Effect? As you can see in the videos above there seems to be a slight jump or skip in between certain numbers. This is because of the time it takes for the clock pulse to get from one flip flop to another. You can see it in an oscillation of the circuits. As it divides by two each time the distance between the rising edge and falling edge increases. It looks like a ripple, which is why it is called the ripple effect.