Create a NOR Gate!

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Introduction: Create a NOR Gate!


You will build a fully functioning NOR gate, and see what is going on inside of them!
for more on LOGIC gates, see Jimmy Proton's Channel as well as his LOGIC GATES INST'ABLE

You can find a PDF of this Inst'able attached to the last step.

Step 1: Materials


Materials:
  • Twelve 10Kohm resistors
  • Eight NPN transistors
  • Lots of small jumper wires
  • A Breadboard to assemble it on
That is it. Short list, huh?

        10Kohm resistors are not essential. What I mean by that is that you may substitute them for different resistors. Any combination of resistors with a value between 4.7 Kohms and 100 Kohms will work in this project.

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:
Photobucket
 

Full sized image below:
Photobucket

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...?


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


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===


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    32 Comments

    Can I use 1K resistors? I have currently 20.

    You can use 1 kohm resistors.

    Sidenotes:

    With 1 kohm resistors, each NOR gate will consume more power, depending on its state.

    You could use100 kohm resistors instead of 10 kohm resistors (the exact value is not critical).

    Higher resistor values may limit the speed of the gates.

    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............

    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

    if i make 1 bir memory can i store data in it
    if not what is its use

    for hobby electronics, these are great. there are many times when i want to save a single value.

    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.

    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.