D Flip Flops
Alright so the D Flip Flop (74LS74) is kinda the basic flip flop. It has six segments/parts to it; on the top is the preset, on the right hand side is Q and Qnot, on the bottom is Clear, and on the left is D and Clock (Refer to Drawing). To begin, Q is an output and Qnot is the same output but inverted i.e.(Q = 1, Qnot = 0). BUT, Q is not always 1, the output of Q depends on D, and D can just be whatever it wants, so for example D=1, Q=1, or D=0, Q=0 (remember we are using binary so everything is either a 1 or a 0). NOW, Q only reflects D when the clock (our input) pulses. So the clock pulses and either on the rising or falling edge of that pulse Q will look at D and mimic it. Finally, preset and clear are the big bosses, if one of them isn't inputing a signal of 1, the entire flip flop just shuts down and doesn't do anything.
Above is just an example from the Intro Activity, showing what the timing diagram for a D flip flop would look like during specific situations.
One thing you should note on the picture above is the triangle on the Clock, a triangle denotes that this flip flop operates on the rising edge of the pulse, while a triangle and a dot denote that it operates on a falling edge. The dots are actually inverters, that is why they are on Preset and Clear, so that they are always one and the flip flop can function, its on Qnot as well so that it will be the inverse of Q.
One thing you should note on the picture above is the triangle on the Clock, a triangle denotes that this flip flop operates on the rising edge of the pulse, while a triangle and a dot denote that it operates on a falling edge. The dots are actually inverters, that is why they are on Preset and Clear, so that they are always one and the flip flop can function, its on Qnot as well so that it will be the inverse of Q.
JK Flip Flops
Alright so JK Flip Flops are a little more complicated than D Flip Flops. So Q is still our output, and Qnot is still its opposite, Clock is still our input and Preset and Clear still have the power to shut everything down. Now however, Q does not look at D but at two new parts called J and K. Basically when the clock pulses and Q checks to see what it is supposed to be doing; IF J and K are both 0 then nothing happens, Q stays whatever it is, IF J is 0 and K is 1 then Q automatically goes to 0, IF K is 1 and J is 0 then Q automatically goes to 1, and IF BOTH J and K are 1 then Q changes to its opposite state.
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Here is an example from the Activity of a JK Flip Flop and its Timing Diagram. As you can see it functions as previously described.