# Thread: I just spent five hours building this...

1. ## I just spent five hours building this...

A 4 bit full adder circuit :O My very first useful digital circuit.

The schematic is really messy, I didn't spend a lot of time making it neat, and it probably has a bit of mistakes when I translated the expressions over to the schematic.

Really, it shouldn't take longer than 30 minutes to design this, I just haven't done it before so o.o

2. Are you becoming a electronics engineer or something? Looks confusing to me.

3. what's the round line under the or gate?

4. Any type of engineering you do, you have to cover electricity stuff.
~

5. i think itz Boolean algebra and the structure seems like combination of AND, OR n NOR gates.
not sure though.

6. It just looks like a ton of square penises.
Seriously bro learn how to draw a straight line. You related to Michael J. Fox?

7. ## The Following User Says Thank You to bowlcut For This Useful Post:

[MPGH]Psychotic (11-01-2012)

8. Originally Posted by noob555
what's the round line under the or gate?
Its an XOR gate. Output is only high if one input and not the other is high.

I can just give you the expression for schematic I derived from the truth tables if you want (if that is what you are trying to get from the schematic) :S

CarryFlagOut = CarryFlagIn AND (Ax XOR Bx) OR (Ax AND Bx)
Outx = Ax XOR Bx XOR CarryFlagIn

I literally just repeat that logic for however many bits I want to add. Only because there is no carry for the first bit, I just use the same expression only with CarryFlagIn as zero and you get a simple XOR and AND gate.

Originally Posted by max620
i think itz Boolean algebra and the structure seems like combination of AND, OR n NOR gates.
not sure though.
Yeah, it is boolean algebra, but those are XOR gates not NOR gates. NOR gates look like plain OR gates but with a negation bubble at the output.

The next step is to put this into minecraft :O

Originally Posted by Arhk
Any type of engineering you do, you have to cover electricity stuff.
~
Not sure about that. I doubt boolean algebra would be of any use to a civil engineer.

Originally Posted by Dreamer
Are you becoming a electronics engineer or something? Looks confusing to me.
Yeah, atm I am studying Computer\Electrical Engineering.

9. I will pretend to understand this schematic, apparently drawn by an ingenious 5 year old, and applaud your efforts.

10. use a ruler man,
looks like some smart stuff.

11. I'm currently studying in Electrical Enginering, and i dont even get anything on this scheme so use a ruler next time, and explain stuff.

12. Originally Posted by Jetamay

Not sure about that. I doubt boolean algebra would be of any use to a civil engineer.

Yeah, atm I am studying Computer\Electrical Engineering.
At my school everyone had to do a semester on it.
~

13. Originally Posted by The Reaper
I'm currently studying in Electrical Enginering, and i dont even get anything on this scheme so use a ruler next time, and explain stuff.

I already did, in my previous response to Noob555's post. And it isn't that bad. I mean sure, the lines aren't straight, but you can deduce expressions from this. The gates are quite distinctive.

Designs for 4 bit full adders seem to be fairly consistent with each other, there really isn't much to explain other than to give the expressions I designed the circuit with.

Its an XOR gate. Output is only high if one input and not the other is high.

I can just give you the expression for schematic I derived from the truth tables if you want (if that is what you are trying to get from the schematic) :S

CarryFlagOut = CarryFlagIn AND (Ax XOR Bx) OR (Ax AND Bx)
Outx = Ax XOR Bx XOR CarryFlagIn

I literally just repeat that logic for however many bits I want to add. Only because there is no carry for the first bit, I just use the same expression only with CarryFlagIn as zero and you get a simple XOR and AND gate.

14. Originally Posted by Jetamay
Its an XOR gate. Output is only high if one input and not the other is high.

I can just give you the expression for schematic I derived from the truth tables if you want (if that is what you are trying to get from the schematic) :S

CarryFlagOut = CarryFlagIn AND (Ax XOR Bx) OR (Ax AND Bx)
Outx = Ax XOR Bx XOR CarryFlagIn

I literally just repeat that logic for however many bits I want to add. Only because there is no carry for the first bit, I just use the same expression only with CarryFlagIn as zero and you get a simple XOR and AND gate.

Yeah, it is boolean algebra, but those are XOR gates not NOR gates. NOR gates look like plain OR gates but with a negation bubble at the output.

The next step is to put this into minecraft :O

Not sure about that. I doubt boolean algebra would be of any use to a civil engineer.

Yeah, atm I am studying Computer\Electrical Engineering.
ohh
Its a xor gate
I'm taking a digital electronics class myself! It's interesting.

15. Good job, theres some complex shit right there..

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