Using a 74HC74 Integrated Circuit

74HC74-pins

74HC74 Pins

I received some advice to use a 74HC74 flip-flop for a project idea I’ve had. I’ve never used an integrated circuit so I thought a good first step was to put together a very simple demo I could hack around with it. This IC is big enough it actually provides two flip-flops, one on each side as you can see from the pin diagram on the right. Both sides work the same, but are completely independent other than sharing power and ground. I’m only using the first side for this example.

 

As I press the buttons connected to CLR and PRE, you can see the outputs (Q and not Q) alternate. I’ve set the data (D) and clock (CLK) pins to ground. The truth table for the 74HC74 comes in handy to understand what’s going on.

74HC74-truth-table.png

Here is a simplified wiring setup because it’s hard to see how everything is connected in the video.

74HC74-wiring.png

Also check out Combining 74HC74 & 555 Integrated Circuits.

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