JK flip-flop as a monostable / static protection

[Tim Dorrington]

Hi - 2 questions that I'm hoping you could help with...

1) I'm designing a circuit which currently uses half a CMOS 4027 dual
JK flip-flop. I need to add a monostable circuit to it, so that I get
a clean pulse (0.5 seconds approx - timing not too important) suitable
for clocking a counter IC from a push switch. I was going to use a
NE555 but wonder if there's a way I can use the other half of the 4027
instead? I assume that the push button will control the clock input,
and there would need to be some sort of R-C arrangement between the
output and the J/K inputs...?

2) If there's a possibility of someone touching a contact linked to a
CMOS IC's input, is there a simple way of preventing/limiting static
damage to the IC? The application is a game where the player might
cause a 2 contacts to touch (one for the IC input, one for the supply
voltage).

Thanks for any information,
Tim.

 

[Kevin Aylward]

Tim Dorrington wrote:

Hi - 2 questions that I'm hoping you could help with...

1) I'm designing a circuit which currently uses half a CMOS 4027 dual
JK flip-flop. I need to add a monostable circuit to it, so that I get
a clean pulse (0.5 seconds approx - timing not too important) suitable
for clocking a counter IC from a push switch. I was going to use a
NE555 but wonder if there's a way I can use the other half of the 4027
instead?

Of course.

I assume that the push button will control the clock input,
and there would need to be some sort of R-C arrangement between the
output and the J/K inputs...?

Why don't you think about it some more? It has sets and resets and
stuff, with things doing things on a clock signal. Frankly, if you cant
figure out this one out your tod...jesus wept dude...what about tying
the jk to a 1, and the output to the reset via an RC...?


Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Kevin Aylward]

Terry Pinnell wrote:

"Kevin Aylward" <kevin@anasoft.co.uk> wrote:

Tim Dorrington wrote:
Hi - 2 questions that I'm hoping you could help with...

1) I'm designing a circuit which currently uses half a CMOS 4027
dual JK flip-flop. I need to add a monostable circuit to it, so
that I get a clean pulse (0.5 seconds approx - timing not too
important) suitable for clocking a counter IC from a push switch.
I was going to use a NE555 but wonder if there's a way I can use
the other half of the 4027 instead?

Of course.

I assume that the push button will control the clock input,
and there would need to be some sort of R-C arrangement between the
output and the J/K inputs...?

Why don't you think about it some more? It has sets and resets and
stuff, with things doing things on a clock signal. Frankly, if you
cant figure out this one out your tod...jesus wept dude...what about
tying the jk to a 1, and the output to the reset via an RC...?


Kevin Aylward

TO KEVIN:
Why don't *you* think about it some more? If he knew how to do it then
would he have sought help? Frankly, if you don't know how to be civil
... Jesus wept dude... what about offering a practical solution

I did.

*without* the lecture?

It gives people a much needed, jolly good kick up the arse. Its been
done to me many times, and I'm thankful for it. We use to dream of
getting kicked up the arse when we were young. Sheer luxury it was.

I must admit the use of the phrase "I'm designing a circuit.." made an
impact. The reality is that, if someone just knew even the basics enough
to "design" a circuit, this particular one is a no brainer. It designs
itself, if you know what the terminals do. I certainly agree that some
things need more hand holding, but some others don't.


Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Kevin Aylward]

John Dyson wrote:

Kevin Aylward wrote:


*without* the lecture?


It gives people a much needed, jolly good kick up the arse. Its been
done to me many times, and I'm thankful for it. We use to dream of
getting kicked up the arse when we were young. Sheer luxury it was.

I must admit the use of the phrase "I'm designing a circuit.." made
an impact. The reality is that, if someone just knew even the basics
enough to "design" a circuit, this particular one is a no brainer.
It designs itself, if you know what the terminals do. I certainly
agree that some things need more hand holding, but some others don't.

It seems like some 'pros' sometimes forget that there are alot of
individuals (less and less so, however) who are newbies and haven't
immersed themselves into electronics technology.

Of course, everyone is a beginner at some point, but even beginners have
to figure certain things for themselves. In this case, the assumption is
that the poster knew what a jk does. If so, the solution is truly
trivial, even for beginners. As I said, sometimes one reasonable hard
knock is enough to get people thinking for the rest of their lives.

I would say its standard, and correct, practice for educators to make
students work a bit rather than be given it all on a plate. I will point
out that it goes without saying, that yes, sometimes educators can
expect too much, or not give enough initial background. I just did not
perceive this to be so in this case here.

I'd sure like to
see a resurgence of an electronics hobby (note the 'basics'
newsgroup), and a friendlier attitude would be helpful.

What happened to Robert?

Arrogance doesn't help anyone, perhaps hurting the person who asks
questions, and making the arrogant 'expert' truly appear to be
a jerk.

But a show me the truth, don't pull any punches can do a lot of good.
Sure, it might be a bit annoying at first, but you dont half remember it
more.

Not all electronics people are 'jerks', and it would be
good if you helped to prove this assertion.

I think one needs to lighten up a bit. I only said it was good enough
for the lord Jehovah to eat himself.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Dana Raymond]

I remember a few times when I was just learning about digital electronics
back in my twenties. The arrogant answers of "Why should I help you with
this design" for very simple newbie questions stung!

And, I can honestly say, that I have always tried to help others if I feel I
can, or at least make an effort. Even when consulting I try to provide
'value added' at the beginning of the process by being informative - that
helps a lot of smaller companies figure out if they even need to contract
services.

As well, I learned while tutoring in HS that I learned a lot myself by just
covering the material with another, and especially explaining it. Believe
me, a principal is much more 'yours' if you have to find 3 good analogies to
explain it.

And the questions can be fun as well. Try explaining conservation of
mass/energy to someone who asks "But, WHY doesn't a perpetual motion machine
work?"

If I think that someone is looking for a shortcut due to lazyness then I
just don't participate. If someone is trying to accomplish something but
doesn't seem to have even basic knowledge, then I may pull out if the next
step is I have to do the design for them.

Just my two cents - not aimed at anyone in particular.

Dana Frank Raymond


"Kevin Aylward" <kevin@anasoft.co.uk> wrote in message
news:SkM3b.666$b82.312084@newsfep1-win.server.ntli.net...

Terry Pinnell wrote:
"Kevin Aylward" <kevin@anasoft.co.uk> wrote:

Tim Dorrington wrote:
Hi - 2 questions that I'm hoping you could help with...

1) I'm designing a circuit which currently uses half a CMOS 4027
dual JK flip-flop. I need to add a monostable circuit to it, so
that I get a clean pulse (0.5 seconds approx - timing not too
important) suitable for clocking a counter IC from a push switch.
I was going to use a NE555 but wonder if there's a way I can use
the other half of the 4027 instead?

Of course.

I assume that the push button will control the clock input,
and there would need to be some sort of R-C arrangement between the
output and the J/K inputs...?

Why don't you think about it some more? It has sets and resets and
stuff, with things doing things on a clock signal. Frankly, if you
cant figure out this one out your tod...jesus wept dude...what about
tying the jk to a 1, and the output to the reset via an RC...?


Kevin Aylward

TO KEVIN:
Why don't *you* think about it some more? If he knew how to do it then
would he have sought help? Frankly, if you don't know how to be civil
... Jesus wept dude... what about offering a practical solution

I did.

*without* the lecture?


It gives people a much needed, jolly good kick up the arse. Its been
done to me many times, and I'm thankful for it. We use to dream of
getting kicked up the arse when we were young. Sheer luxury it was.

I must admit the use of the phrase "I'm designing a circuit.." made an
impact. The reality is that, if someone just knew even the basics enough
to "design" a circuit, this particular one is a no brainer. It designs
itself, if you know what the terminals do. I certainly agree that some
things need more hand holding, but some others don't.


Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[John Jardine]

Kevin Aylward <kevin@anasoft.co.uk> wrote in message
news:SkM3b.666$b82.312084@newsfep1-win.server.ntli.net...

Terry Pinnell wrote:
"Kevin Aylward" <kevin@anasoft.co.uk> wrote:

Tim Dorrington wrote:
Hi - 2 questions that I'm hoping you could help with...

[clip]
I must admit the use of the phrase "I'm designing a circuit.." made an
impact. The reality is that, if someone just knew even the basics enough
to "design" a circuit, this particular one is a no brainer. It designs
itself, if you know what the terminals do. I certainly agree that some
things need more hand holding, but some others don't.


Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

I've noticed over the years that peoples 'learning styles' are radically
different. What's good for one, *completely* fails on another.
This flip-flop question blew straight by me. To answer it I'd have had to
dig out a data sheet. I use 'em, regard 'em as boring and find the working
knowledge 'sticks' for about 5 minutes. If the need arises it's simply a
case of rummaging a data book and picking something that looks tasty. I have
though, the luxury of hindsight.
A neat full answer was provided by Terry P's circuit. From this drawing it
was simple to backtrack and remind myself of what a JK device does.
This compares to the time wasting struggle I had years ago, trying to get to
grips with a description of JK operation as provided by a Texas Instuments
data book. I look back and even now know it was a piece of s**t.
Learning would have been much, much, much, faster and pleasurable, if the
Internet, the newsgroups and the Terry P's had been around at the time.
regards
john

 

[John Dyson]

Kevin Aylward wrote:

I would say its standard, and correct, practice for educators to make
students work a bit rather than be given it all on a plate. I will point
out that it goes without saying, that yes, sometimes educators can
expect too much, or not give enough initial background. I just did not
perceive this to be so in this case here.

I'd sure like to
see a resurgence of an electronics hobby (note the 'basics'
newsgroup), and a friendlier attitude would be helpful.


What happened to Robert?

Arrogance doesn't help anyone, perhaps hurting the person who asks
questions, and making the arrogant 'expert' truly appear to be
a jerk.

But a show me the truth, don't pull any punches can do a lot of good.
Sure, it might be a bit annoying at first, but you dont half remember it
more.

Not all electronics people are 'jerks', and it would be
good if you helped to prove this assertion.

I think one needs to lighten up a bit. I only said it was good enough
for the lord Jehovah to eat himself.

Note that 'lightening up' should include avoiding ANY insults to a

beginner who just might be still enjoying himself. Please try avoiding
ruining an interested beginner. Don't take on the attitude that you
are an educator, but rather a helpful, more experienced individual.

A beginner will get enough of the 'arrogant educator' attitudes in their
lives.

For lightening up, yes, please do so...

John

 

[Robert Monsen]

I, for one, would like to thank all the people who take time to read and
respond to these (mostly beginning) questions. Even a little 'kick'
sometimes gets my marbles rolling in the right direction.

Regards,
Bob Monsen

"John Jardine" <john@jjdesigns.fsnet.co.uk> wrote in message
news:bioq12$s9q$1@newsg3.svr.pol.co.uk...

Kevin Aylward <kevin@anasoft.co.uk> wrote in message
news:SkM3b.666$b82.312084@newsfep1-win.server.ntli.net...
Terry Pinnell wrote:
"Kevin Aylward" <kevin@anasoft.co.uk> wrote:

Tim Dorrington wrote:
Hi - 2 questions that I'm hoping you could help with...

[clip]
I must admit the use of the phrase "I'm designing a circuit.." made an
impact. The reality is that, if someone just knew even the basics enough
to "design" a circuit, this particular one is a no brainer. It designs
itself, if you know what the terminals do. I certainly agree that some
things need more hand holding, but some others don't.


Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.


I've noticed over the years that peoples 'learning styles' are radically
different. What's good for one, *completely* fails on another.
This flip-flop question blew straight by me. To answer it I'd have had to
dig out a data sheet. I use 'em, regard 'em as boring and find the working
knowledge 'sticks' for about 5 minutes. If the need arises it's simply a
case of rummaging a data book and picking something that looks tasty. I
have
though, the luxury of hindsight.
A neat full answer was provided by Terry P's circuit. From this drawing it
was simple to backtrack and remind myself of what a JK device does.
This compares to the time wasting struggle I had years ago, trying to get
to
grips with a description of JK operation as provided by a Texas Instuments
data book. I look back and even now know it was a piece of s**t.
Learning would have been much, much, much, faster and pleasurable, if the
Internet, the newsgroups and the Terry P's had been around at the time.
regards
john

 

[Tim Dorrington]

Just to say thanks to Terry for the circuit - I'll give it a go as
soon as I can.

To Kevin... I'm sure it's frustrating when it appears that people
don't make an effort to solve their problems. What I posted was
polite, to the *basics* newsgroup only (no such thing as a 'stupid'
question, I thought), was for a solution that has evaded me one way or
another after a reasonable time messing about with the circuit... and
I'm not a student asking for help with their homework. I'm not sure I
would have come up with Terry's solution - I'm only a hobbyist and am
just trying my best to understand a subject I find enjoyable. The
nearest I'd managed to get was a debounced bistable circuit. That
said, you tried to point me in the right direction, and I'm grateful
for that at least - it *was* the bit with the passive components that
tripped me up. I just think a little more patience would be more
helpful - especially in this particular newsgroup.

Thanks again folks.
Regards,
Tim.

 

[Kevin Aylward]

John Jardine wrote:

Kevin Aylward <kevin@anasoft.co.uk> wrote in message
news:SkM3b.666$b82.312084@newsfep1-win.server.ntli.net...
Terry Pinnell wrote:
"Kevin Aylward" <kevin@anasoft.co.uk> wrote:

Tim Dorrington wrote:
Hi - 2 questions that I'm hoping you could help with...

[clip]
I must admit the use of the phrase "I'm designing a circuit.." made
an impact. The reality is that, if someone just knew even the basics
enough to "design" a circuit, this particular one is a no brainer.
It designs itself, if you know what the terminals do. I certainly
agree that some things need more hand holding, but some others don't.


I've noticed over the years that peoples 'learning styles' are
radically different. What's good for one, *completely* fails on
another. This flip-flop question blew straight by me. To answer it
I'd have had to dig out a data sheet. I use 'em, regard 'em as boring
and find the working knowledge 'sticks' for about 5 minutes. If the
need arises it's simply a case of rummaging a data book and picking
something that looks tasty. I have though, the luxury of hindsight.
A neat full answer was provided by Terry P's circuit.

I've been playing guitar since I was 11. If I teach myself a new tune,
it sticks. If I read it from music, I forget it by the next day.

If we go back to what I actually posted, prior to terry I might add,
what could have given the most satisfaction in finalising the result?

From this
drawing it was simple to backtrack and remind myself of what a JK
device does. This compares to the time wasting struggle I had years
ago, trying to get to grips with a description of JK operation as
provided by a Texas Instuments data book.

Wow....I suppose I must be missing something. It was introduced to me as
a clocked RS bistable, with the exception that 11 toggles it. What more
is there to know.

We have one of two options, ether everyone's normal and I'm a genius,
or...

I look back and even now

know it was a piece of s**t. Learning would have been much, much,
much, faster and pleasurable, if the Internet, the newsgroups and the
Terry P's had been around at the time.

Well, out of around 10,000 posts, I don't think there that many where
I'm too abrupt.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Kevin Aylward]

Tim Dorrington wrote:

Just to say thanks to Terry for the circuit - I'll give it a go as
soon as I can.

To Kevin... I'm sure it's frustrating when it appears that people
don't make an effort to solve their problems. What I posted was
polite, to the *basics* newsgroup only (no such thing as a 'stupid'
question, I thought), was for a solution that has evaded me one way or
another after a reasonable time messing about with the circuit... and
I'm not a student asking for help with their homework. I'm not sure I
would have come up with Terry's solution - I'm only a hobbyist and am
just trying my best to understand a subject I find enjoyable.

I started as a hobbyist. I agree that at the very beginning, even the
most basics need to be taught clearly such that the student can get a
feel of what's going on.

In your case, you stated that you were using a JK. I took the assumption
that you would therefore know what it does. i.e. a clocked set reset
bistable, with the addition that j=k=1 toggles it. This level of
knowledge would imply to me that you also were aware of RC time
constants.

What I will say is this. I taught myself amplifier design by studying in
detail other amplifiers. Armed with only the basics, I reinvented for
myself why such and such was the way it was. I don't believe that I am
special in this way. I would say I understand amplifier design in much
greater detail than those that simple learned by simple route.

The
nearest I'd managed to get was a debounced bistable circuit. That
said, you tried to point me in the right direction, and I'm grateful
for that at least - it *was* the bit with the passive components that
tripped me up. I just think a little more patience would be more
helpful - especially in this particular newsgroup.

It depends on what day it is.

I also think that if you had had a bit more patience you would have came
to the solution on your own.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[John Jardine]

Kevin Aylward <kevin@anasoft.co.uk> wrote in message
news:woZ3b.208$Ic6.49306@newsfep2-gui.server.ntli.net...

John Jardine wrote:
Kevin Aylward <kevin@anasoft.co.uk> wrote in message
news:SkM3b.666$b82.312084@newsfep1-win.server.ntli.net...
Terry Pinnell wrote:
"Kevin Aylward" <kevin@anasoft.co.uk> wrote:

Tim Dorrington wrote:
Hi - 2 questions that I'm hoping you could help with...

[clip]
I must admit the use of the phrase "I'm designing a circuit.." made
an impact. The reality is that, if someone just knew even the basics
enough to "design" a circuit, this particular one is a no brainer.
It designs itself, if you know what the terminals do. I certainly
agree that some things need more hand holding, but some others don't.


I've noticed over the years that peoples 'learning styles' are
radically different. What's good for one, *completely* fails on
another. This flip-flop question blew straight by me. To answer it
I'd have had to dig out a data sheet. I use 'em, regard 'em as boring
and find the working knowledge 'sticks' for about 5 minutes. If the
need arises it's simply a case of rummaging a data book and picking
something that looks tasty. I have though, the luxury of hindsight.
A neat full answer was provided by Terry P's circuit.

I've been playing guitar since I was 11. If I teach myself a new tune,
it sticks. If I read it from music, I forget it by the next day.

Neat but unfair analogy. By random strumming(?) you, (or even I) may be
fortunate to come across a unique chord or pleasing sequence of notes.
Electronics stuff needs a shed load of fixed ground rules to be learnt and
applied before anything good can even begin to start to happen.

If we go back to what I actually posted, prior to terry I might add,
what could have given the most satisfaction in finalising the result?

(Point noted about precedence). The most satisfying outcome would be that
'flash of understanding' based on a *analysing a good example of the craft*.
You did actually answer Tim's question but it was cryptic to the point of
impenetrability. It read as if an irritable half of you was struggling to
take control of the helpful half.

From this
drawing it was simple to backtrack and remind myself of what a JK
device does. This compares to the time wasting struggle I had years
ago, trying to get to grips with a description of JK operation as
provided by a Texas Instuments data book.

Wow....I suppose I must be missing something. It was introduced to me as
a clocked RS bistable, with the exception that 11 toggles it. What more
is there to know.

Yes, my Texan nightmare was actually a 7470 ... but ... the revealing
statement is, "It was introduced to me". This implies the possibility of a
question being raised and some expert human feedback given in response. Tim
has not that luxury.

We have one of two options, ether everyone's normal and I'm a genius,
or...

I think the rest of us are but easily damaged mortals.

I look back and even now
know it was a piece of s**t. Learning would have been much, much,
much, faster and pleasurable, if the Internet, the newsgroups and the
Terry P's had been around at the time.

Well, out of around 10,000 posts, I don't think there that many where
I'm too abrupt.

In the couple of years of reading your posts I've taken on board a lot of
interesting stuff and a new slant on things. I've got to 'know' your
writing style and yes!, of the posts I've read, only a few I might regard
as unreasonably abrupt.
A K.A. post is a K.A. post. Myself, I take it as I find it and will look at
what's in there. Just the same as talking to a mate down the pub.
That's just my view though.
OTOH, many people may be unaware of the person and from the writing style,
induct elements (wholly without reason of course ;-) of pedantry? or
arrogance? or intransigence? or bloody mindedness? or even helpfulness!.
(Y'know ... the stuff we mortals all suffer from but won't admit to!)

Does Tim know of these things?.
Will he unfairly have marked you down as a twat? (and by logical default,
the rest of us poor sodding plebs ;-).
regards
john

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.