# Use a JK flip flop to implement a SR flip flop

Discussion in 'Homework Help' started by Karamelg1, Apr 25, 2007.

1. ### Karamelg1 Thread Starter Member

Mar 25, 2007
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0
Hi,

I am instructed to implement a SR flip flop from a JK flip flop. I was wondering if it was as simple as just hooking up an S input into the J part of the ff, and a R input into the K input? My professor has the solution equation as J=S and K=R, but I am trying to actually draw the diagram. Any help would be appreciated. Thanks!

2. ### Papabravo Expert

Feb 24, 2006
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1,850
As you know the SR flip-flop is typically not clocked. It is asyncronous. A JK on the other hand has four syncronous input possibilities: set, clear, toggle and hold. In order to determine the next state you must specify both J AND K. In my opinion it is not sufficient to sepcify J=S and K is a don't care for the set function.

Some JK flip-flops have asyncronous preset and clear inputs which only serves to obscure the issues.

3. ### recca02 Senior Member

Apr 2, 2007
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try reading abt k-map, there might also be solved examples using k map to convert J K to S R in a book dealing with k map, i have done this before but do not remember it.

4. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
I do not think a karnaugh map will be of any use here. They are for minimization AFTER you have a boolean equation. They are useless before you have one.

5. ### recca02 Senior Member

Apr 2, 2007
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i m not as experienced as you mr P.B.,
but i do remember solving this kind of problems using k map.
in which the inputs come out as a combination of previous state and s and r inputs.
also sometimes the conversion does seem illogical as might happen in case of J K
to S R conversion.
but for other conversions like s r to j k or d to t
it does make some sense.
i wud have liked to show you the example i solved but due to some reasons(MY exams) i can not solve it right now as i will also have to brush up on the concept. may be on jun 20 i wud be in a position to do so if required.

6. ### Karamelg1 Thread Starter Member

Mar 25, 2007
12
0
Thanks for your help. It is completely confusing to me ~ My final exam is tomorrow, so I guess I shall just keep my fingers crossed