Bertus, you're a legend!

What's the name of the cat?

 

Hello,

The cat in the avatar is called Toto.
She is the oldest cat I have.
She is 16 years now.

As you might know I have 5 cats:

Bertus

 

So, to bring this up again...

I've attached a copy of the circuit which I have re-drawn, as I believe that there a few mistakes on the original circuit. (e.g there was one too many Vcc's and the pin numbers were confuddled).

Could anyone tell me if the this is correct?

Sparky

 

I translated your .doc into something more compatible for this site. I think you have missed some points, as they are not one common circuit as you show.

1. A prescaler is a simple divider circuit, as well as input conditioner. Its sole job is to reduce the frequency by 10 or 100 so the counter can handle frequency being measured. The article shows two prescalers, one for high frequencies, one for lower frequencies, to allow a freq counter to be used for much higher ranges. Because its output is a exact fraction of the input frequency (÷10,100, or 1000) it is not gated.

2. The time base is just that, a precision frequency that will allow precision counting of pulses. If a gate is on for 1 second, the the counter will show true frequency. If the AND gate is on for 0.001 seconds, it will show the frequency ÷ 1000.

http://www.jameco.com/Jameco/Products/ProdDS/49411TI.pdf

A 74HC132 is a fast quad NAND Schmitt Trigger, you don't show where it goes to the the counter. The counter is the real heart of a freq counter. Generally the BCD to LED/LCD decoders (like the 4511 or 7447, which if you look closely are very similar to each other) have a latch and hold circuit to keep the display stable will the actual counter chips take the next sample (and count).

 

Thanks Bill.

What I'm trying to do is figure out how all these different circuits fit together.

Although the circuit diagrams have little labels showing where (I assume) they join together, I thought I'd just join the two together as shown.

Have I done this incorrectly?

How should I go about 'joining' the circuits together?

Thanks.

 

The counter itself is the common theme. The prescaler goes in front of the counter, usually as an add on accessory (it can be removed).

The gate/timebase circuit is on the input and is an integral part of the counter. I suppose you could make the prescaler a permanent part of the freq counter, but remember that the prescaler is usually removable, as it reduces the resolution of the counter substantially.

I think the main thing I have a problem with is there is no freq out for the counter circuit itself. It is not really a big deal, but the majority of the circuit is not acknowledged (a big black box marked counter). The time base also interacts with this box, when the gate is off the number on the BCD counters (call them registers) are transfered to the latch/hold and display circuitry.

The time base is part of the freq counter and is not removable. It is actually part of that big black box, as is the AND gate.

 

So the circuits which were one that website don't show the whole, complete project?

 

It had the other section, you missed it I suspect. It is the counter. I did not show it large scale because it is too big, and reducing the size would make it unreadable.

There are many ways to make a counter, this is only one. For example, a 4029 has the decoder and counter in one chip.

 

I hadn't missed that part, I just hadn't been able to find the table to table table out yet!


I'm trying to make a piece of test equipment which can measure the frequency. Put a probe in there and read off the frequency from the display.


Would I need to build all of these circuits together to accomplish this, or do I just need one?

 

I am out of time, but I will try to get the block diagram drawn up tonight. I suspect it will make things more clear.

A freq counter is really simple, it is a straight forward counter, say 6 digits, with a latch/hold input (not strictly needed, but it makes the appearance much cleaner) and a reset input to clear the last count.

The gate lets the signal through, the counter counts. When the gate turns off, the counter displays its count.

Simple. Later guy!

 

Thanks Bill, I really appreciate your time.

No sweat with the diagram, I'm not needing it soon so no need to rush.

Thanks again,

Sparky

 

Hi guys,

just wondering if anyone can provide me with some more help? I'd really like to get a pcb design produced before christmas, 'cause I can get my school to make it for me.

Thanks,

Sparky

 

Sorry Sparks, I had intended to send you a design but I guess I forgot. I'll come up with something.

 

<same here>

Could you include me in that design?

 

Some specs needed:

1. Input voltage level
2. How many digits
3. Max frequency
4. CMOS or TTL

 

I don't know if you really want to re-invent the wheel here.
There's a 6-digit CMOS 10Mhz frequency counter over on Laurier Gendron's site:
http://members.shaw.ca/roma/fc.html

I didn't read through and verify all of Sparky's requirements, but Laurier's design is really quite simple - and it should be quite easy to build.

If higher frequencies/more capabilities are needed, it would really make much more sense to go to a microcontroller-based design, as the parts count would decrease even more, and reliability would improve.

 

I understand you Sgt. Sparky wants to learn how to design a system using standard ICs which I will be happy to provide. The only reduction I will use is a combination 4511 latch/driver which will simplify the wiring a bit.

This is very similar to the schematic Bill posted at post #28.

http://forum.allaboutcircuits.com/attachment.php?attachmentid=35543&d=1319221510

This is a design exercise.

The Intersil ICM7226 is a single chip 8-digit 10MHz Frequency Counter if you wish to go that route.

 

Yeah looks good to me. Total insanity to re-invent the wheel.

 

Here's one I made with a PIC. It connects to a PC via serial and it's not brilliant, but I find it useful on occasion.
http://www.marksphotos.info/fg/

 

Here's one I made with a PIC. It connects to a PC via serial and it's not brilliant, but I find it useful on occasion.
http://www.marksphotos.info/fg/

Impressive.

You should be programming in C or Basic though mostly.