# Homework Circuit - design a digital decoder.

#### Leite33

Joined Nov 28, 2015
57
Dear friends
I have a difficult home work and i want your help. I have to create a circuit on a paper.
" Create a circuit production digitized par values for a number of three bits using (xyz)
j) decoders 2 to 4 (with a non-inverted outputs and without activated entrance) and gates OR
ii)Only multiplexers 2 to 1 (without activated entrance) and gates NOT

#### shteii01

Joined Feb 19, 2010
4,644
I see two problems.
One of them is language.

#### Leite33

Joined Nov 28, 2015
57
I am sorry english is not my mother language.
Create a circuit to produce a bit of positive rate for a number of 3 binary bits (xyz) using:
1.decoders 2 to 4 (with non inverted outputs and without activated entrance) and OR gates
2. only multiplexers 2 to 1 (without activated entrance) and AND gates

My circuit will have entrances x y z and output 1 bit using decoders and OR gates

#### WBahn

Joined Mar 31, 2012
30,242
You need to describe more fully what you mean by "a bit of positive rate" for a "number of 3 binary bits"?

Perhaps a couple examples might help get your meaning across.

#### Dodgydave

Joined Jun 22, 2012
11,318
Use the words "inputs" for entrance,

What's positive rate,is that a positive output signal?

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#### Leite33

Joined Nov 28, 2015
57
Yes my output must be one positive byte(8bits) like 10010000 for example and not 10000000

#### Leite33

Joined Nov 28, 2015
57
Any help?

#### Leite33

Joined Nov 28, 2015
57
How i can built a small circuit with 2 for example decoder 2-4 and some OR gates that should have inputs xyz (3 inputs)

#### Leite33

Joined Nov 28, 2015
57
Greek

#### ISB123

Joined May 21, 2014
1,236
Post the same question in Greek pretty sure we have a Greek guy around here.

#### WBahn

Joined Mar 31, 2012
30,242
Yes my output must be one positive byte(8bits) like 10010000 for example and not 10000000
Why is 1001000 considered "one positive byte" while 1000000 is not?

It sounds like your input is a 3-bit value, xyz, where x, y, and z are each one bit. Where does this requirement that the output be eight bits come from?

Can you describe, in words, how YOU would look at the inputs and determine what the output should be?

#### panic mode

Joined Oct 10, 2011
2,799
maybe bit4 is sign bit

#### WBahn

Joined Mar 31, 2012
30,242
Maybe. But unless the TS can communicate the situation clearly, we are all just guessing.

#### Leite33

Joined Nov 28, 2015
57
Ok i will try be more specifiec. I want to make a simple circuit with 3 inputs x y z that should produce a byte (for example 11011011) by using 2 decoders and one OR gate if this is possible

#### ISB123

Joined May 21, 2014
1,236
Make a schematic which describes how you would design a such circuit.
We cant help unless you show us some effort be it wrong or correct.

#### WBahn

Joined Mar 31, 2012
30,242
Ok i will try be more specifiec. I want to make a simple circuit with 3 inputs x y z that should produce a byte (for example 11011011) by using 2 decoders and one OR gate if this is possible
But how does the output relate to these three inputs?

Are the three inputs three bits, three bytes, three giraffes, what?

#### hp1729

Joined Nov 23, 2015
2,304
Dear friends
I have a difficult home work and i want your help. I have to create a circuit on a paper.
" Create a circuit production digitized par values for a number of three bits using (xyz)
j) decoders 2 to 4 (with a non-inverted outputs and without activated entrance) and gates OR
ii)Only multiplexers 2 to 1 (without activated entrance) and gates NOT
A three input decoder? Look at the data sheet for a decoder like the 74138 and modify it as needed.

#### Whatashame

Joined Nov 30, 2015
88
But how does the output relate to these three inputs?

Are the three inputs three bits, three bytes, three giraffes, what?
This is for WBahn. Your a pain in the a*#. I'm staring at"Ohm's law. Vx I= W. Thank you! By the way if you ever get hit with 600 volts you better pray it's AC volts and not DC volts. You might fly through a wall with AC but with DC your stuck on it until your fried or someone hits you off with a baseball bat. I hit you off if need be. I'm leaving this site. On it one day. Be kind to new bed and all people. I used lay terms. You must be an engineer. I bow down, Almighty. [Name and phone number removed]. This was directed to WBahn, the most perfect person.

MOD NOTE: It's not a good idea to put personal contact info into publically accessible forums -- spam bots routinely sweep them up.

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#### JoeJester

Joined Apr 26, 2005
4,390
By the way if you ever get hit with 600 volts you better pray it's AC volts and not DC volts. You might fly through a wall with AC but with DC your stuck on it until your fried or someone hits you off with a baseball bat.
The emphasis is "can" be stuck. I've been hung up on a +900V DC circuit for over what seemed like a couple of seconds until I managed to free myself. The circuit was a 300 mA circuit.

In my defense, and there really wasn't a defense because I hadn't taken the time to read the technical manual, I didn't know that equipment used switched screen grid voltage to key the transmitter vice switched B+. It was that time that I chose to stand up to anyone who viewed myself or my technicians "reading the manual" as not working. After all, we were overhauling quite a few equipments that we were not taught in the schools or at previous units. I had a not so nice heart to heart conversation with those senior to me, I was a Petty Officer Second Class at the time. They asked me to talk about it during the training session I had scheduled the following week, and did express my opine on the importance of RYDM ... Read Your Dam Mannual.