1. Home
  2. Hobby Electronics Basics
  3. Decoder and Inverter

Decoder and Inverter

Hi,

Questions 1 :

How can you use K-Map for 3 to 8 line decoder? The truth table is as folllows

a b c o1 o2 o3 o4 o5 o6 o7 o8

0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 0 1 0 1 1 1 0 0 0 0 0 0 0 1

I know that I can make the boolean equation from the Truth table and can make the decoder circuit using 8 an gates and some inverters? But how can do this using K map. Is it possible to do a K map? Because there are 8 out puts not one!

Question 2: If you are allowed to use just one NAND gate then, how many ways can you come up with an inverter?

I know atleast two ways to solve this problem. I can tie the two inouts of the NAND gate together or tie one input to ground permanently.

But my problem is that how can use K map to solve this problem.

If I use K map then I come up with the followng equation

A' + B' = Y

Can I solve this problem using K map?

jess

Reply to
jsscshaw88
Loading thread data ...

No. Tie it high.

Why do you want to use a kmap? That's mostly of historical interest.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

I want to use K map for many reasons. The thing is how can I solve the problems using K Map?

Please tell me how if its possible!

jess

Reply to
jsscshaw88

Will the answer still be valuable after finals week?

--
www.wescottdesign.com
Reply to
Tim Wescott

They're so obvious aren't they?

Reply to
Tom Biasi

The OP is probably using KMAP, the program...

I use it frequently to reduce truth tables to logic. (But I can still do Karnaugh maps by hand :-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

The usual Karnaugh map gives you a single output from 3 or 4 inputs. (Two inputs is trivial, and if you have more than 4 inputs, the map gets a bit unwieldy.)

Your Karnaugh map for each output would be pretty simple. In fact, it's so simple that you can write down each output by inspection from the truth table, e.g.

o3 = !a * b * !c

Combining them to synthesize the cascaded-gate implementation is much better done algebraically.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

This one:

formatting link

is free and does up to 8 variables

formatting link
is limited to 5)

Reply to
David Eather

If you read my OP, you will notice that I am not asking how to do K Map and I am not asking for the answers.

I am aksing that if you have three inputs and eight different outputs then can one build K map to solve the probelm.

The same problems can easily ne solved by just writing bollean equations.

jess

Reply to
jsscshaw88

We use logic complers! Most of what we do is in FPGAs, and they are LUT based, not classic AND/OR elements.

"Glue logic" and ECL circuits are generally so simple, we design them by inspection.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Certainly. I use KMAP mostly to analyze chips I am behavioral modeling to minimize what I do with my B-logic functions.

I'm close to releasing a 4538 one-shot model that actually acts like the real-deal, down to including the external R/C... with half as much logic ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.