Help with logic truth tables

[Des]

Hi
It is years since I dabbled in electronics. I need a J K Flip Flop
(4000 series) J=K=1 Toggles on clock pulse (positive or negative).
J=K=0 No change. I thought all JKs did this but 4027 truth table is
strange.

 

[Bruce Varley]

"Des" <desotuatail@aol.com> wrote in message
news:a7dad2d8-3083-4e31-a453-e53ce9cb57a3@n6g2000vbz.googlegroups.com...

Hi
It is years since I dabbled in electronics. I need a J K Flip Flop
(4000 series) J=K=1 Toggles on clock pulse (positive or negative).
J=K=0 No change. I thought all JKs did this but 4027 truth table is
strange.

Que? This one is exactly as per your description.

http://www.datasheetcatalog.org/datasheet/philips/HEF4027BP.pdf

Or are you saying that the actual device isn't behaving in accordance with
the truth table? In that case, the problem could be unterminated pins,
supply rail noise or contact bounce on an input.

 

[Dennis]

"Des" <desotuatail@aol.com> wrote in message
news:a7dad2d8-3083-4e31-a453-e53ce9cb57a3@n6g2000vbz.googlegroups.com...

Hi
It is years since I dabbled in electronics. I need a J K Flip Flop
(4000 series) J=K=1 Toggles on clock pulse (positive or negative).
J=K=0 No change. I thought all JKs did this but 4027 truth table is
strange.

Download one of the free spice simulation packages and have a play.

 

On Thu, 5 Jan 2012 22:14:59 +0800, "Bruce Varley" <bv@NoSpam.com> wrote:

"Des" <desotuatail@aol.com> wrote in message
news:a7dad2d8-3083-4e31-a453-e53ce9cb57a3@n6g2000vbz.googlegroups.com...
Hi
It is years since I dabbled in electronics. I need a J K Flip Flop
(4000 series) J=K=1 Toggles on clock pulse (positive or negative).
J=K=0 No change. I thought all JKs did this but 4027 truth table is
strange.


Que? This one is exactly as per your description.

http://www.datasheetcatalog.org/datasheet/philips/HEF4027BP.pdf

Or are you saying that the actual device isn't behaving in accordance with
the truth table? In that case, the problem could be unterminated pins,
supply rail noise or contact bounce on an input.

He's expecting the thing to toggle on either edge of the clock,

not a standard thing. Datasheet says it flips on rising clock
edge only.

Perhaps try an xor with RC to one input, to make a clock pulse
___/\___ from each incoming edge?

Grant.

 

[yaputya]

<omg@grrr.id.au> wrote in message newsu2cg7tabd4rj5l5ehedtqr8ssgn59r4sp@4ax.com...

On Thu, 5 Jan 2012 22:14:59 +0800, "Bruce Varley" <bv@NoSpam.com> wrote:


"Des" <desotuatail@aol.com> wrote in message
news:a7dad2d8-3083-4e31-a453-e53ce9cb57a3@n6g2000vbz.googlegroups.com...
Hi
It is years since I dabbled in electronics. I need a J K Flip Flop
(4000 series) J=K=1 Toggles on clock pulse (positive or negative).
J=K=0 No change. I thought all JKs did this but 4027 truth table is
strange.


Que? This one is exactly as per your description.

http://www.datasheetcatalog.org/datasheet/philips/HEF4027BP.pdf

Or are you saying that the actual device isn't behaving in accordance with
the truth table? In that case, the problem could be unterminated pins,
supply rail noise or contact bounce on an input.

He's expecting the thing to toggle on either edge of the clock,
not a standard thing. Datasheet says it flips on rising clock
edge only.

He said positive OR negative, not positive AND negative.
I don't think he meant both, eh?

 

[terryc]

yaputya wrote:

omg@grrr.id.au> wrote in message newsu2cg7tabd4rj5l5ehedtqr8ssgn59r4sp@4ax.com...
On Thu, 5 Jan 2012 22:14:59 +0800, "Bruce Varley" <bv@NoSpam.com> wrote:

"Des" <desotuatail@aol.com> wrote in message
news:a7dad2d8-3083-4e31-a453-e53ce9cb57a3@n6g2000vbz.googlegroups.com...
Hi
It is years since I dabbled in electronics. I need a J K Flip Flop
(4000 series) J=K=1 Toggles on clock pulse (positive or negative).
J=K=0 No change. I thought all JKs did this but 4027 truth table is
strange.

Que? This one is exactly as per your description.

http://www.datasheetcatalog.org/datasheet/philips/HEF4027BP.pdf

Or are you saying that the actual device isn't behaving in accordance with
the truth table? In that case, the problem could be unterminated pins,
supply rail noise or contact bounce on an input.

He's expecting the thing to toggle on either edge of the clock,
not a standard thing. Datasheet says it flips on rising clock
edge only.

He said positive OR negative, not positive AND negative.
I don't think he meant both, eh?

Then there are those who understand digital and those that don't.

It might be better if the Original Poster explains what the requirement
is, rather than persist trying to make a flawed implementation work.