Design Lab Work

Today’s Digital Systems Design lab somehow managed to totally confuse the hell out of me… Since I couldn’t seem to get anything done while I was there, I figured I would poke at it when I got home.

The basic gist of the assignment is this:

wire a simple logic circuit and look at its output to gain experience with
correct breadboarding techniques. Then we will look at how CMOS (complementary
metal-oxide-semiconductor) logic circuits differentiate between a logical 0 and logical 1 state. As you know, these circuits use voltage to determine logical states, so there is some threshold which the voltage must be clearly greater than or less than in order to correspond clearly to one of the states. The difference between the output voltage and the input threshold is known as the noise margin.

This assignment uses a Texas Instruments 74HC00 Quad NAND IC, hooked up to a function generator on the inputs, and output to a scope. The lab manual gave us these diagrams and a few pointers to get us going.

NAND_block

NAND.circuit

I also grabbed the datasheet from TI’s website, which gave me the pinouts.

IMG_0454

Each of the gates is labeled 1-4, with A & B inputs, and Y output. I’m still a bit confused as to how exactly the function generator, power supply, and scope plug into this, but I think I’ve managed to get a very pretty breadboard working here at home.

IMG_0453

All of the red wires are 5V positive, the black goes to ground, the green wire is the input to the function generator, and the yellow will connect to my scope. (I’ve since looped it like the green one.)

Oh yes, I must give credit for my fairly neat breadboards to Michael Ciuffo at ch00ftech for his awesome video advice about breadboarding. Basically, he’s got some of the slickest breadboard skills I’ve ever seen, and which you can watch here:

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