# [HELP]Logic Gates Application

Discussion in 'Homework Help' started by francesmardc, Mar 7, 2014.

1. ### francesmardc Thread Starter New Member

Mar 6, 2014
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0
Hello,

I am having a difficulties on what project should i create using Logic Gates, Led, Resistors, buttons, switches ONLY. im needing of a simple project just like the traffic light application. can anyone have an idea what should i make just a simple one.

p.s. im thinking of a game show buttons or buzzer game. that only one LED should lit on at any given time. only need 2 buzzer/buttons just like the quiz game on shows. and i saw alot of that on the web but it requires a 555 timer and my prof. wont allow us to use 555 timer. so please anyone have an idea on how to make it without 555 chip? please show a diagram.

Oct 2, 2009
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3. ### tshuck Well-Known Member

Oct 18, 2012
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675
One could implement a linear feedback shift register for pseudorandom number generation. Or even count very fast and stop when a button is released...

The clock could be generated by a few gates.

Without crystals
With crystals

4. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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can't use digital number display either.

5. ### tshuck Well-Known Member

Oct 18, 2012
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Who said anything of the sort?

A few LEDs arranged in a "H" pattern is all you need for display...

6. ### alfacliff Well-Known Member

Dec 13, 2013
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if you cant use a 555, why not use a couple of gates as an oscilator? or a dual one shot chip?

7. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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what is the equivalent of 555 timer on a basic gates? as i said im newbie and im not sure what im saying lol

8. ### MrChips Moderator

Oct 2, 2009
12,636
3,454
A dice uses a pattern of seven dots. Use seven LEDs to represent the dots.

You can build an oscillator using a single inverting schmitt trigger or using three inverters.

9. ### tshuck Well-Known Member

Oct 18, 2012
3,531
675
Like This:

This allows you to represent all possible combinations of a dice roll with the seven LEDs MrChips was referring to.

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10. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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any diagram? upon searching the net i saw alot but it uses some timers and others that which we are not allowed to use.

so how does it work? randoming numbers 1-7?

11. ### #12 Expert

Nov 30, 2010
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Does, "we" mean your school class?

12. ### djsfantasi AAC Fanatic!

Apr 11, 2010
2,905
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Ok, so one thing we know is that you can't use 555, timers or others.

What logic gates CAN you use? Are flip-flops allowed? How about counters? If we knew what gates you CAN use, it'd eliminate suggestions less than useful.

13. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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definitely no, its just that im not into this electronics things, ofcourse theres this subject on my course, im taking up computer science btw. but upon searching the net ive came up with this forum and here i am asking for a help.

we are only allowed to use 7400, 7402, 74ls32, 7408, 7404 or the ic for basic logic gates.. CAN'T use flip flops. CAN'T use counter.

14. ### MrChips Moderator

Oct 2, 2009
12,636
3,454
Doesn't leave you with much to work with.

How about a digital combination lock? Set the correct combination and press a button to unlock.

15. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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yea to much to work with because we are only allowed to use limited things.

that could be another id love to have. any logic?

16. ### takao21203 Distinguished Member

Apr 28, 2012
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makes totally sense- we are only allowed to use ......

I'd tell the instructor "This does not make sense".

Indeed you can't do so much with just a few these chips.

Besides you could build a flip flop from logic gates as well.

17. ### takao21203 Distinguished Member

Apr 28, 2012
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463
you can make a ring oscillator from NOT gates- 3 or 5 or more. 47uF to 220 uF and LEDs.

I don't have a schematic but it's not too hard to breadboard.

18. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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i know that feel i just need a simple one project that have a purpose..he gave us example like a simple traffic light.

anyway im thinking of thi:

i have a 6 input, let 1,2,3,4,5,6
example displaying 1 and 2 on the "H" pattern digital dice
1 = 1
2 = 0
3 = 0
4 = 0
5 = 0
6 = 0

then the out put for the leds, let leds be a,b,c,d,e,f,g
the only led that will lit on is letter "d" same like the dice
a-------e

b---d---f

c-------g

example two produces a #2 on the dice.
1 = 0
2 = 1
3 = 0
4 = 0
5 = 0
6 = 0
the 2 leds will be light on the leds are "a" and "g" like the dice

and so on..

19. ### MrChips Moderator

Oct 2, 2009
12,636
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That's a good start.

20. ### francesmardc Thread Starter New Member

Mar 6, 2014
12
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problem is i cant picture out the combination and logic gates to use.. can you please help me?

ive been searching the net for a couple of hours but i can't search the exact term for it