Instructables

Create a NOR Gate!

Step 2: The Schematic


The Schematic of a NOR gate is shown above, as well as the schematic of a generic Quad NOR Gate IC. The latter is rather big, so I have manually inserted it below.

HOW DOES THIS WORK?
The function of a NOR gate is as follows:
  • When both inputs A and B are LOW, our NOR gate outputs a 1 (HIGH state)
  • If either A or B is HIGH, our NOR gate outputs a 0 (LOW state)
  • And finally, if both inputs A and B are HIGH, our NOR gate will output a 0 (LOW state)
We can see this illustrated in the below graph:
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Full sized image below:
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With these schematics, you can build one NOR gate, or two thousand!
Be creative, and  share some pictures of your own!

Step 3: NOR Gate Uses...?

Picture of NOR Gate Uses...?

There are tons of uses for NOR gates.
One of the most famous of which is using two of them to make one bit of memory (as seen above)
There are tons of uses for nor gate  and the only limit is what you can think of.
Share a picture of your NOR gates in action in the comment section below!

Step 4: GREAT UTILITIES

Picture of GREAT UTILITIES

Here are some awesome things to keep you busy with your breadboard and circuit design!

An AWESOME Schematic & PCB design software

Transistor Gates

the ULTIMATE collection of logic chip data sheets

(CadSoft: Eagle shown above)

Step 5: ===PDF File===


That's great! Even a 7402 quiescent draw is 8-27ma I'm seeing 3.5ma draw on a red LED and 1K resistor here. Now if you made an CMOS part I'd have more faith in 1000% those run in the microamp range. I suppose it'd all hinge on what you connected to your output. Typically small transistors can supply about 150ma each. So your circuit (the quad one) looks like it could draw better than a half an amp to me depending.

These go on sale a lot for about $3 a piece:

Even if the meter doesn't work the leads are worth at least that! But so far all I've bought have been OK.

Here is one crazy thing I made with a lot of transistors once:

(its a 10 channel logic probe)

It drew like an amp and a half! Which as I said rather surprised me. Now I use current meters while I am prototyping just to keep an eye on things. Though often I'll use an analog meter for that task, with a healthy supply of fuses on hand.
flag............
Man, I just love NOR gates, so far I built 10
jensenr30 (author)  smartbuilderperson3 years ago
awesome! thanks for the comment. it's people like you that keep me interested in making more guides and how-to's on electronics for instructables.com.

"Follow" me to get notifications for my new inst'ables.

I'll be making one on a 9x9 LED matrix very soon. I'm currently building it and it is a fun-ass project. I can't wait to share the experience with my followers!
all the best,
ryan
robot13983 years ago
if i make 1 bir memory can i store data in it
if not what is its use
jensenr30 (author)  robot13983 years ago
for hobby electronics, these are great. there are many times when i want to save a single value.
pfred23 years ago
Have you measured the current draw of this circuit? I built a project once using a lot of transistors and it turned out to draw a lot more current than I thought it would so I figured I'd ask.
jensenr30 (author)  pfred23 years ago
I tested that once and I now for get the value. I don't have a multimeter at the moment, so I'll have to get back to you on the exact number of milliamps.
What I CAN tell you in the mean time is that the circuit used at least 1000% less current than a single LED wired in series with a 1Kohm resistor
That's great!  Even a 7402 quiescent draw is 8-27ma  I'm seeing 3.5ma draw on a red LED and 1K resistor here. Now if you made an CMOS part I'd have more faith in 1000% those run in the microamp range.  I suppose it'd all hinge on what you connected to your output. Typically small transistors can supply about 150ma each. So your circuit (the quad one) looks like it could draw better than a half an amp to me depending.

These go on sale a lot for about $3 a piece:

http://www.harborfreight.com/7-function-digital-multimeter-90899.html

Even if the meter doesn't work the leads are worth at least that! But so far all I've bought have been OK.

Here is one crazy thing I made with a lot of transistors once:
http://img219.imageshack.us/img219/6605/p6280033.jpg

(its a 10 channel logic probe)

It drew like an amp and a half! Which as I said rather surprised me. Now I use current meters while I am prototyping just to keep an eye on things. Though often I'll use an analog meter for that task, with a healthy supply of fuses on hand.
jensenr30 (author)  pfred23 years ago
SRAM? awesome! do you have a schematic? I'd love to see it!
I might somewhere I made that a long time ago and like I said it wasn't that swift. It did work, but just drew too much current operating. This was awesome:

http://img708.imageshack.us/img708/7615/p7100104.jpg

Although it drew a fair amount of current itself running, something like 5 amps. It's not all there in that picture. It is missing its display board among other things:

http://img708.imageshack.us/img708/1643/p7100090.jpg

I think for having built such things maybe I'm not all here either?
jensenr30 (author)  pfred23 years ago
that is beast.
This is great! Would a C945 transistor work, I know its NPN but i wanted to make sure before i bought a couple hundred of them?
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Actually the C945 transistors are $1 cheaper for the same amount (on ebay).
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No, they were in a bag.
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Well i'm glad I didn't, thanks for your concern and your welcome!
jensenr30 (author)  Jimmy Proton3 years ago
P.S.
Never buy any electronic component without a data sheet. It can totally screw things up.
MROHM jensenr303 years ago
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pfred2 MROHM3 years ago
I scavenge parts and especially with transistors I can't always find data sheets. But bipolar transistors are pretty easy to test out. I'm testing some out here:

http://img196.imageshack.us/img196/6414/pict0576h.jpg

They're hiding under this heatsink:

http://img713.imageshack.us/img713/2244/pict0579s.jpg

Sometimes even with a datasheet I still have to curve trace the things to match them in some circuits. Two transistors rolling off the line one after the other are different. A sad and true story indeed!
jensenr30 (author)  pfred23 years ago
interesting.
jensenr30 (author)  Jimmy Proton3 years ago
The only transistor I have hands-on experience with is the C900 and it works fine. The only thing that is strange about it is the pin placement. instead of E, B, and C, it is E, C, and B. I like this pin placement now that I have gotten used to it and having the base on one side of the transistor is really nice.
Send me a link to where you are buying it from and the data sheet! I'd like to take a look at it
jensenr30 (author)  Jimmy Proton3 years ago
I doubt you will have any trouble with these transistors. make sure to remember the new pin layout! I like to use sticky labels for all of my electronics. I cut out small pieces of the label and paste them on to ICs. As for transistors, try having an individual baggy for them labeled "ECB"

in summary: Go for it!
I'm pretty exited about this!
jdege3 years ago
If you can build either a NAND or a NOR gate, you can build any logical gate, AND, OR, XOR, etc. And you can build flip-flops, and hence you can build memory. And that means you can build a computer.

http://www.amazon.com/Elements-Computing-Systems-Building-Principles/dp/0262640686/
jensenr30 (author)  jdege3 years ago
This is why I LOVE digital electronics!!!
Analog is more fun.

http://img143.imageshack.us/img143/7867/testout.jpg

Bench testing an overdrive effect I made using a home brewed 12 watt amp, analog adjustable power supply and signal generator.

Digital is just on and off. Well it is supposed to be when it works right. Though I did the digital thing back in the day as well.

http://img708.imageshack.us/img708/1643/p7100090.jpg

http://img708.imageshack.us/img708/7615/p7100104.jpg
pfred2 jdege3 years ago
But first you'd need to build a power station to run the thing and a basketball court to house it in! There are reasons they threw all those parts on IC dies you know?
This was so good that I bought 300 transistors, 900 resistors (300 of each:1k 10k 100k), 9 meters of fine solder, and 3 1500 point prototype PCB's!!! I spent about $27.50!
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jensenr30 (author)  Jimmy Proton3 years ago
Do the resistors have good quality? Are the leads sturdy but not THICK? I would love to buy those resistors, seeing as how they are 1/3 of a cent ea.!

I would really appreciate your input! thank you!
jensenr30 (author)  Jimmy Proton3 years ago
It is a nice feeling when I have a fresh stock of resistors! LOL!