Count 1ns pulse

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

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

How have you connected them?

Assuming that is all correct, As a first step, I would add another

74HC4520 and check the result.

Not to mention minimum pulse time?

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Tim Wescott
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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.

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

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

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 :)

"Tam/WB2TT"

** 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

"John Fields"

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

** 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

"David L. Jones"

** 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

Hi David im using a HP 8011A Pulse generator.

Thanks

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.

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.

How are you generating a 1ns pulse with a generator that is only capable of generating a 25ns pulse at best?

Dave :)

** You are wasting your time on this f****it, fake "Rocket Scientist".

He is taking YOU for a big ride - all the way down.

........ Phil

Derhhh sorry Dave you are right i misread the scope it is in fact 1usec timebase not as i previously thought 1ns must get my eyes tested.

Thread closed!

Dave :)