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I Recently found the need to add 2 new Digital Logic Gates Circuits to my collection.

There are alot of combinations using the basic logic circuits that can produce
strange effects but there are times when your project just wont work without them so
i hope these 2 will prove to be more than useful.


Transistors used in these circuits can be any npn transistor such as BC547, BC548, BC549, 2N3904 etc.
Diodes can be virtually any type so long as they can handle the reverse voltages in your design.
LED's were only used to provide a visual reference to show these circuits in action.

Experiment on breadboard first before you use any of the circuits shown, All were tested before publishing and All of the component values can easily be played around with to meet your needs.

inputs can be virtually any signal source from timers to oscillators and more, or even push buttons and reed switches and so on.


in both circuits you will notice inputs a and b have 2 terminals, in the built circuits
both A's are connected together and both B's are connected.
all of the 10K resistors can be lower values if you get any problems.



XOR (Exclusive OR)

With a normal OR Gate, one or both of inputs that are used will turn the output on,
but with This XOR Circuit Only one of the 2 inputs are allowed to be used at one time.

If input A or B is switched on then the output is switched on, but if both are used
then the output stays switched off.



XNOR (Exclusive NOR)

With a normal NOR gate, one or both of the inputs will turn the output off,
but like the XOR Gate only one of the XNOR inputs can be used at any one time
to switch the output off.


If input A or B is switched on then the output is switched off, but if both are used
then the output stays switched on.


<p>A Big Thanks to everyone who has viewed and commented on this Instructable.</p><p>Just a quick update really on this topic, and to let you all know that i recently redesigned these circuits to work on less power, and use less components. </p><p>Although the new ones aren't ready to view yet, i am hoping to create some proper circuit designs along with some photos, maybe videos too and do a massive update.</p><p>Although this could be months away yet, I've really been inspired by so many people on YouTube, and i want to create a channel with regular uploads,<br>i have lots of my own designs and ideas that aren't on here yet, and i think everyone would appreciate seeing things working before they have a go too.</p><p>here's a quick CAD Snapshot of the new designs, they still need tinkering with but they're nearly ready.</p>
<p>hey dean, i really interested to your circuits, i want to know, do you already test your circuit for series with like 10 other gates? because recently i build a one bit full adder, but the output is too low (LED barely lights and it can't drive another transistor)</p>
<p>i only tested them one at a time, for a bigger project i might have to change some of the small transistors for MOSFETs and remove one or two resistors, which in some cases can cause less power loss. i haven't tried anything new yet so i can't really help with that one.</p>
<p>I have made a version which requires only 3 transistors:</p>
Hello, Dean. I intend to use your circuits for a small project. Could you forward your actual name so I could do proper referencing, please.<br><br>Hope to hear from you.<br>Thanks in anticipation.
<p>Same name as my username, Dean Potts<br>Thanks.</p>
<p>dude, this is really impressive. The xor is critical in basic processing(which all comes back to the addition circuit). Typically, an xor is made of four nands. Each nand takes two transistors, making an xor take 8. More transistors=higher propagation delay. By taking out three(as in your design), you may have just opened up the possibility to massively increase speeds in circuits and computers! I know that i will be using this design! Seriously, it's people like you that we need to be working on engineering better and faster circuits and chips for major companies.</p>
<p>Thank you, these circuits were intended for that exact reason, to speed things up, to save on pcb space and cost too. I hope you find good use for these in your own designs.</p>
<p>hi, i want to make a circuit for a conveyor belt on which a carrier is taking a single box after each 4 inch but sometimes two boxes drop and it causes machine to stuck.( __==___=___=___ ) (=)single box- (==) two boxes, graphically. my logic is to give a clock cycle as reference frequency and input from proximity sensor when they both matches the circuit remain as well as machine but whenever the input single extends from its original frequency of square wave the machine should go OFF to stop scrap. pls guide me how i can give reference square wave and input, XOR gate satisfy my conditions. like whenever the input n reference wave mismatch its goes OFF.</p>
Do you have any tips for cascading these gates?
i havent tried yet with full circuits, but the transistors base and emitter pins are in most cases the answer, the LEDs in the designs are indicators of the circuits final path but as for combining more than one circuit you dont need all of the components, as little as an extra 2 resistors and 1 transistor. <br>for example: to make the XOR Gate. i used an AND Gate on the left to switch an OR Gate on the bottom right off, if the OR Gate wasnt there it would just be a NAND. <br> <br>i hope that has answered you question and not confused you.

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