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Count 1ns pulse
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Paul Taylor
electronics forum beginner


Joined: 10 Feb 2005
Posts: 45

PostPosted: Wed Jul 19, 2006 3:45 pm    Post subject: Re: Count 1ns pulse Reply with quote

"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...
Quote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

Thanks

Paul

Sorry - follow on from that i know that 2 to the power 16 = 65k but im

getting 1023 as the result
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Tam/WB2TT
electronics forum Guru Wannabe


Joined: 17 May 2005
Posts: 106

PostPosted: Wed Jul 19, 2006 4:01 pm    Post subject: Re: Count 1ns pulse Reply with quote

"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...
Quote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

Thanks

Paul

Did you ever look at the maximum clock frequency of an HC4520?
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pomerado@hotmail.com
electronics forum beginner


Joined: 19 Jun 2006
Posts: 41

PostPosted: Wed Jul 19, 2006 4:07 pm    Post subject: Re: Count 1ns pulse Reply with quote

Paul Taylor wrote:
Quote:
"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

Thanks

Paul

Sorry - follow on from that i know that 2 to the power 16 = 65k but im
getting 1023 as the result

How have you connected them?

Assuming that is all correct, As a first step, I would add another
74HC4520 and check the result.
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Tim Wescott
electronics forum Guru


Joined: 04 May 2005
Posts: 707

PostPosted: Wed Jul 19, 2006 4:07 pm    Post subject: Re: Count 1ns pulse Reply with quote

Tam/WB2TT wrote:
Quote:
"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...

Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

Thanks

Paul


Did you ever look at the maximum clock frequency of an HC4520?


Not to mention minimum pulse time?


--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html
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John Fields
electronics forum Guru


Joined: 24 Mar 2005
Posts: 3260

PostPosted: Wed Jul 19, 2006 4:55 pm    Post subject: Re: Count 1ns pulse Reply with quote

On Wed, 19 Jul 2006 16:45:04 +0100, "Paul Taylor"
<paul.taylor@uea.ac.uk> wrote:

Quote:
"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

---
This is starting to get silly. You need to learn how to read a data
sheet or take this to sci.electronics.basics.

A 1ns wide pulse every 5ns is a 200MHz clock. the HC4520 is rated
for 68MHz max.

The clock pulse width is specified as 8ns minimum for Vcc = 5V.
1ns is almost an order of magnitude too narrow.
---

Quote:
Sorry - follow on from that i know that 2 to the power 16 = 65k but im
getting 1023 as the result

---
You're lucky you're getting anything.

How do you have the counters hooked up?

And, BTW, since you're having so much trouble getting this together
and you've bought the PMT and the PAD, why don't you just buy the
counter module from Electron Tubes and be done with it?

--
John Fields
Professional Circuit Designer
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Tam/WB2TT
electronics forum Guru Wannabe


Joined: 17 May 2005
Posts: 106

PostPosted: Wed Jul 19, 2006 11:48 pm    Post subject: Re: Count 1ns pulse Reply with quote

"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...
Quote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

Thanks

Paul

How sacred is the 1 ms? Your best bet is to prescale the 200 MHz by 4, using

high speed JK flip flops; then count the number of cycles in 4 ms. You will
still want something better than the HC4520s, though. Unless the output is
machine readable, why not use decade counters? Note that if you are not
planning on having 6 digits of display, you could prescale by 10, or even
100, and just move the decimal point , and keep the 1 ms gate time. So, for
a /100 prescale, a count of 1999 would be 199.9 MHz.

Tam
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Bill Sloman
electronics forum Guru


Joined: 12 May 2005
Posts: 1080

PostPosted: Thu Jul 20, 2006 12:23 am    Post subject: Re: Count 1ns pulse Reply with quote

Paul Taylor wrote:
Quote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the total
number of pulse in 1ms this according to my calculator totals 200,000, Im
using two 74HC4520 Dual 4-bit synchronous binary counter to give me the 16
bits required, i don't seem to be getting the correct output reading, why?

The 74HC4520 isn't fast enough.

Check out the 74AC163 or 74ACT163 - even they need about 3.5nsec wide
clock pusles before they will count, but they can be strung together -
see figure 2 in the data sheet - to manage the 50MHz you will need,
though not the 200MHz you are generating with your pulse generator.

--
Bill Sloman, Nijmegen
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David L. Jones
electronics forum Guru Wannabe


Joined: 07 Jun 2005
Posts: 286

PostPosted: Thu Jul 20, 2006 3:01 am    Post subject: Re: Count 1ns pulse Reply with quote

Paul Taylor wrote:
Quote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the total
number of pulse in 1ms this according to my calculator totals 200,000, Im
using two 74HC4520 Dual 4-bit synchronous binary counter to give me the 16
bits required, i don't seem to be getting the correct output reading, why?

As others have said, the 74HC4520 is wayyyyy too slow for this
application, as will be every other 74xxxxxxx series device.

Just how are you generating this 1ns pulse?

Dave Smile
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Phil Allison
electronics forum Guru


Joined: 20 May 2005
Posts: 1368

PostPosted: Thu Jul 20, 2006 3:18 am    Post subject: Re: Count 1ns pulse Reply with quote

"Tam/WB2TT"
Quote:

"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9ljtv$881$1@cpca14.uea.ac.uk...
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total number of pulse in 1ms this according to my calculator totals
200,000, Im using two 74HC4520 Dual 4-bit synchronous binary counter to
give me the 16 bits required, i don't seem to be getting the correct
output reading, why?

Thanks

Paul

Did you ever look at the maximum clock frequency of an HC4520?



** He doesn't understand what frequency is.

See his sig fie:


Paul Taylor BSC (Hons)
Electronics Technician
School of Environmental Science
University of East Anglia
Norwich
NR4 7TJ

Phone: +44 (0)1603 592502
Fax: +44 (0)1603 591327



** A science grad employed as a tech is a fraud.





....... Phil
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Phil Allison
electronics forum Guru


Joined: 20 May 2005
Posts: 1368

PostPosted: Thu Jul 20, 2006 3:20 am    Post subject: Re: Count 1ns pulse Reply with quote

"John Fields"

Quote:
This is starting to get silly.


** Wake up - it got silly a long time ago.


Quote:
And, BTW, since you're having so much trouble getting this together
and you've bought the PMT and the PAD, why don't you just buy the
counter module from Electron Tubes and be done with it?


** See the fool's sig file:


Paul Taylor BSC (Hons)
Electronics Technician
School of Environmental Science
University of East Anglia
Norwich
NR4 7TJ

Phone: +44 (0)1603 592502
Fax: +44 (0)1603 591327


** He is a science grad who has faked his way into a job he has no clue how
to do.




........ Phil
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Phil Allison
electronics forum Guru


Joined: 20 May 2005
Posts: 1368

PostPosted: Thu Jul 20, 2006 3:24 am    Post subject: Re: Count 1ns pulse Reply with quote

"David L. Jones"

Quote:
Just how are you generating this 1ns pulse?


** The OP is posting from the " School of Environmental Science, University
of East Anglia" so has access to all manner of fancy test gear.

He is also a self confessed * Rocket Scientist *.

" Hi martin it is going up in a rocket funded by various other university
along with us from a launch pad in Norway. "


ROTFLMAO !!!!





....... Phil
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Paul Taylor
electronics forum beginner


Joined: 10 Feb 2005
Posts: 45

PostPosted: Thu Jul 20, 2006 7:56 am    Post subject: Re: Count 1ns pulse Reply with quote

"David L. Jones" <altzone@gmail.com> wrote in message
news:1153364491.069220.250950@h48g2000cwc.googlegroups.com...
Quote:
Paul Taylor wrote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total
number of pulse in 1ms this according to my calculator totals 200,000, Im
using two 74HC4520 Dual 4-bit synchronous binary counter to give me the
16
bits required, i don't seem to be getting the correct output reading,
why?

As others have said, the 74HC4520 is wayyyyy too slow for this
application, as will be every other 74xxxxxxx series device.

Just how are you generating this 1ns pulse?

Dave :)

Hi David im using a HP 8011A Pulse generator.


Thanks
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Paul Taylor
electronics forum beginner


Joined: 10 Feb 2005
Posts: 45

PostPosted: Thu Jul 20, 2006 8:04 am    Post subject: Re: Count 1ns pulse Reply with quote

<bill.sloman@ieee.org> wrote in message
news:1153355028.067672.238690@m73g2000cwd.googlegroups.com...
Quote:

Paul Taylor wrote:
Hi all i still haven't solved the counter problem here is another problem
link to the first problem - i know have a pulse generator with which im
generating a 1ns pulse every 5ns so i want to take this and count the
total
number of pulse in 1ms this according to my calculator totals 200,000, Im
using two 74HC4520 Dual 4-bit synchronous binary counter to give me the
16
bits required, i don't seem to be getting the correct output reading,
why?

The 74HC4520 isn't fast enough.

Check out the 74AC163 or 74ACT163 - even they need about 3.5nsec wide
clock pusles before they will count, but they can be strung together -
see figure 2 in the data sheet - to manage the 50MHz you will need,
though not the 200MHz you are generating with your pulse generator.

--
Bill Sloman, Nijmegen


I haven't got to hand any 74AC163, i will have to order some in and give
them a go, The data sheet for the 74hc4520 says that it can read typically a
clock pulse width of 10ns? and a maximum clock pulse frequency of 58Mhz, i
agree that this wont work with my pulse generator set up.
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Paul Taylor
electronics forum beginner


Joined: 10 Feb 2005
Posts: 45

PostPosted: Thu Jul 20, 2006 8:31 am    Post subject: Re: Count 1ns Pulse Reply with quote

So basically According to the electron tubes data sheet for the PAD the
pulse pair resolution is 24ns and the output pulse rise and fall time is 2ns
so say a 5ns pulse will be seen on the output of the pad every 24ns so the
total period is 29ns (frequency 34Mhz) so in effect the 74hc4520 maximum
frequency isn't a problem only the pulse width it will read? so in a
nutshell i need something to read a 5ns pulse any ideas.

Thanks
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Paul Taylor
electronics forum beginner


Joined: 10 Feb 2005
Posts: 45

PostPosted: Thu Jul 20, 2006 9:26 am    Post subject: Re: Count 1ns Pulse Reply with quote

"Paul Taylor" <paul.taylor@uea.ac.uk> wrote in message
news:e9nf10$qrt$1@cpca14.uea.ac.uk...
Quote:
So basically According to the electron tubes data sheet for the PAD the
pulse pair resolution is 24ns and the output pulse rise and fall time is
2ns so say a 5ns pulse will be seen on the output of the pad every 24ns so
the total period is 29ns (frequency 34Mhz) so in effect the 74hc4520
maximum frequency isn't a problem only the pulse width it will read? so in
a nutshell i need something to read a 5ns pulse any ideas.

Thanks

Update - Been in contact with electron tubes and actually spoke to the guy

who built the pad the pulse pair resolution is actually define as 1 cycle
i.e. 24ns from the rising edge of the first pulse to the rising edge of the
second one? so im still faced with finding a counter to count 5ns pulse.

The other idea i have thought of now is to stretch the 5ns pulse to 10ns
then the counter will be able to read the pulse this shouldn't effect
anything.
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