frequency meter

[epilot]

Hello friends,

i have a multimeter called DEC(DEC-890G) it has a frequency meter that is able to count 20kHZ MAX, i need to measure 100kHz max sometimes,
the only way i know is using from a convertor(made of CMOS or TTL logical IC's)i think i can use from 4017 IC but i am not sure if i have any alterative or...

by the way it is very good if someone says me how is the configuration for a such circuit?

any help would be very appreciated

 

[panic mode]

it's called prescaler and it is just divider/counter.
if you choose divide by ten counter, you will get 20kHz signal
when input is 200kHz. this is convenient because it's easy to read.
you could cascade two div by 10 counters to get prescaler 100:1 and be
able to measure up to 2MHz.

 

[epilot]

it's called prescaler and it is just divider/counter.
if you choose divide by ten counter, you will get 20kHz signal
when input is 200kHz. this is convenient because it's easy to read.
you could cascade two div by 10 counters to get prescaler 100:1 and be
able to measure up to 2MHz.

thanks,

since i have no circuit for this job in my hands so can you please draw the circuit that i need?

what about a 4017 counter circuit? i use from the freq that i want to test as a pulser for 4017...

P.s i am in doubt if i can calculate the sine wave with this way too?

 

[panic mode]

it is common practice to condition signal a bit (use protection, amplify if needed, run through schmidt trigger) before feeding it to a scaler. this way any signal can be used (low or high, square or sine...). schmidt trigger can be used to convert signal to square shape required for counter

 

[epilot]

it is common practice to condition signal a bit (use protection, amplify if needed, run through schmidt trigger) before feeding it to a scaler. this way any signal can be used (low or high, square or sine...). schmidt trigger can be used to convert signal to square shape required for counter

well, i have found a 74HC393 divider IC and made the circuit,
can i measure the sine wave directly without schmitt trigger?

 

[Nigel Goodwin]

well, i have found a 74HC393 divider IC and made the circuit,
can i measure the sine wave directly without schmitt trigger?

You can, as long as the signal is large enough for the 393 to convert it to squarewave - so it depends on the input signal strength. With a preamp and schmitt trigger you're looking at probably 10mV to 100mV sensitivity - without it you're looking at a number of volts required.

Try it and see, but it depends completely on what you're trying to do with it.

 

[ikalogic]

ATMEL micro controllers, with a 24 Mhz crystan, can measure up to 500 Khz, look at this project:

**broken link removed**

 

[Nigel Goodwin]

ATMEL micro controllers, with a 24 Mhz crystan, can measure up to 500 Khz, look at this project:

**broken link removed**

That's hardly thrilling?.

A PIC running at only 4MHz can work as a frequency counter upto 50MHz, there was even a VERY old application note at MicroChip showing how - long before Atmel even released their first AVR.

 

[ikalogic]

well, that's what i have read in my AT89C52 book... , but thanks for the note, i'l give it a try, maybe it can measure more than 500 Khz

here is what is written in the book:
"the maximum input frequency that can be accurately counted is the oscillator frequency divided by 24, for our 6 megahertz crystal, the calculation yields a maximum external frequency of 250 KiloHertz"

maybe you meant that i add a prescaler? in that case.. well yes, i guess my AT89C52 could measure up to 500 Mhz easily... but i am talkin about the direct frequency the uC can measure...

 

[Nigel Goodwin]

well, that's what i have read in my AT89C52 book... , but thanks for the note, i'l give it a try, maybe it can measure more than 500 Khz

here is what is written in the book:
"the maximum input frequency that can be accurately counted is the oscillator frequency divided by 24, for our 6 megahertz crystal, the calculation yields a maximum external frequency of 250 KiloHertz"

maybe you meant that i add a prescaler? in that case.. well yes, i guess my AT89C52 could measure up to 500 Mhz easily... but i am talkin about the direct frequency the uC can measure...

So am I, a single PIC, an LCD display (the original application note used multiplexed 7 segment LED's), a 4MHz crystal, a few passive parts - and you can make an auto-ranging 0-50MHz frequency counter.

One popular updated version (with LCD) is at

The trick is to use the internal hardware counter/timer!.

 

[ikalogic]

well in that case.. PIC16 scores a well merited point over the 8051...

 

[Hero999]

So what?

This frequency counter works up to 2.5GHz!
https://hem.passagen.se/communication/frcpll.html

 

[Nigel Goodwin]

So what?

The whole point is NO PRE-SCALER, the article you posted uses a prescaler to divide the incoming frequency down to a lower one (a standard technique in frequency counters for higher ranges).

Interesting it uses a PIC18F though, presumably the 18F could be used for a 50MHz counter on it's own as well?.