up counter schematic equivalent to JK flip flop wont work.

Thread Starter

mershi

Joined May 14, 2017
1
I am trying to build a counter using JK flip flop, and ideally I want to use only 7400, 7408 and 7404 ICs, and a button instead of clock.

what I Did first was simulate the whole thing in logism, used the jk-flipflop(block diagram), and it worked.
here is the schematic: http://i.imgur.com/4qEggqo.png

Right after that, i replaced all of the jk-flipflop(block diagram) with its schematic equivalent and it did not work.
here is the schematic: http://i.imgur.com/lLAcFvh.png

should i use different schematic for the jk flip flop?
 

MrChips

Joined Oct 2, 2009
23,264
What do you mean by "it did not work"?
You have to elaborate, i.e., tell us what it is doing.
Are you testing using LEDs? How are the LEDs connected to the circuit? Which LEDs are lit, which are not lit? Do the LEDs ever change state?

Did you debounce the push button?
 

dl324

Joined Mar 30, 2015
12,805
Welcome to AAC!

To minimize issues with broken links in the future, posting images on this site is preferred.
upload_2017-5-14_8-16-10.png
One flip flop:
upload_2017-5-14_8-21-28.png
lLAcFvh.jpg
Right after that, i replaced all of the jk-flipflop(block diagram) with its schematic equivalent and it did not work.
The circuit looks correct. Did you try one flip flop to make sure it was working?
 

WBahn

Joined Mar 31, 2012
26,398
Circuits like this rely on the propagation delay around the feedback path being longer than the hold time. If the prop delays are zero (which is the case in many simulators by default) then they will not function.
 
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