Honestly, we are good at solving problems but this seems like the OP is asking us to solve his solution. What is the real problem?
What is wrong with a digital readout.
Why is there no access to the analog input of the current situation?
What accuracy is needed?
What range of input voltages are needed?
Does the current meter have automatic range adjustment?

Sir i need no one to solve my problem but i ask to see what others have idea, experience. i said i can use uc(atmel,pic,dspic,fpga,arduino,...etc) but it is nice to see what others have.
thanks all for replay.

 

The color is RED

well, red is a totally different story.

 

Sir i need no one to solve my problem but i ask to see what others have idea, experience. i said i can use uc(atmel,pic,dspic,fpga,arduino,...etc)

Then I'd use a microcontroller to read the multiplexed segments, convert the result to an analog value to drive an unspecified analog display.

If you don't have sufficient I/O's available, you'd need to add some additional hardware. Do you have access to the display multiplex clock?

 

I thought i can do it with pic16f877a y example(i have it). but i need other method from logic ic not uc

Hi,

The final question then is exactly what method is used to scan the segments, digit scan or segment scan. With three digits they probably use segment scan, but there is no guarantee they did it that way. A scope would tell you right away which method is being used.

If they use digit scan then you can read each digit in turn, using the digit select line to latch in the segments, then decode into binary.

If they use segment scan then you have to latch in the digit select for three digits at the same time, once for each segment, then decode all three digits, unless you dont mind going slower and then you can do one digit at a time just repeat for each digit. It depends on how fast the reading can change. Not easy.

To make matters worse, you probably have to use some kind of amplifier to amplify the low segment voltage up to a usable logic level.

Probably also have to check the resulting codes for repetition, to make sure the reading did not change while you were reading the three digits. If you read the same codes twice, it's probably stable.

If you are willing to go the distance it is possible, but not very feasible. It would be wise to look for other ways of doing it such as building your own meter.

 

Sir i need no one to solve my problem but i ask to see what others have idea, experience. i said i can use uc(atmel,pic,dspic,fpga,arduino,...etc) but it is nice to see what others have.
thanks all for replay.

So, to understand this better, there is no reason to do this? You just want to know HOW others would approach this challenge with logic chips as a mental exercise? (apparently a mental exercise for other members - not you)?

 

So, to understand this better, there is no reason to do this? You just want to know HOW others would approach this challenge with logic chips as a mental exercise? (apparently a mental exercise for other members - not you)?

If the TS does not asked for help then this thread should be move to the off topics forum, what do you think ?

 

If the TS does not asked for help then this thread should be move to the off topics forum, what do you think ?

No, it's not off topic; the topic is clearly electronics. Frankly, I enjoyed thinking about the issue.

 

No, it's not off topic; the topic is clearly electronics. Frankly, I enjoyed thinking about the issue.

Yes, I said that because the question still not clear, unless a precisely question and you have the right answer to salve the problem, otherwise it just like a puzzle, an unclear puzzle.

A normally answer that I already posted on #3, it just needs to add a 12 bits adc.

 

If I read his first post literally, I construe that his only contact with the device is with the visible part of the display, i.e., no access to any other part. And if my construction is correct, then the only possible solution is to "read" the display, hence, my suggestion in post #14.

But, I am often guilty of misconstruing things; just ask my wife.

 

Wow, does this bring back memories. The first electronic circuit of any complexity that I designed and built did exactly this. I was a lab assistant for one of my Physics professors, and he had an instrument with a digital display which he wanted to chart on a chart recorder (analog input). Fortunately for us, the display was not multiplexed, and the data was available in a connector as BCD. So it was simply a matter of buffers and ladders designed to convert the BCD data to analog. What made it complex, was that it was a six digit display, and he needed to select any three consecutive digits for the conversion (it was a counter and often the range would be as little as 3 digits). We had a manual switch to do this. Wiring it was a nightmare.

Edited to add: Today, I would use a micro, and it would be much simpler.

Bob

 

Sir

So, to understand this better, there is no reason to do this? You just want to know HOW others would approach this challenge with logic chips as a mental exercise? (apparently a mental exercise for other members - not you)?

this was a replay for some one how said that i post to make other solve my problem. it is not like that.

 

this is what i have done

 

Do you have nay jpg or gif file for the circuit?

 

this is what i have done

I don't open .rar files. Too many stray cats can be hidden in there. Sorry. What is your goal in posting such a file? You need to be able to describe your problem and proposed solution with schematics - .jpg files, for example.

 

I don't open .rar files. Too many stray cats can be hidden in there. Sorry. ...

Why is that? Do you think that looking at contents of an archive is going to blow up your computer? And why say a pdf inside a rar would be more dangerous than any other pdf? (Not that there are any pdfs in this one, but you get the point)

 

I don't open .rar files. Too many stray cats can be hidden in there. Sorry. What is your goal in posting such a file? You need to be able to describe your problem and proposed solution with schematics - .jpg files, for example.

What's stray cats, I have never heard about that, if you using a tool to uncompress .rar file then you can see how many files inside the compressed file before you open them, some windows system may auto un-compress the .zip or .rar files.

 

Why is that? Do you think that looking at contents of an archive is going to blow up your computer? And why say a pdf inside a rar would be more dangerous than any other pdf? (Not that there are any pdfs in this one, but you get the point)

What's stray cats, I have never heard about that, if you using a tool to uncompress .rar file then you can see how many files inside the compressed file before you open them, some windows system may auto un-compress the .zip or .rar files.

I'm not going to bother searching through multiple files to find the file that describes his problem, his proposed solution or his justification for said decisions. If he wants help, he should do the work to present his information appropriately instead of copying all of his recent efforts into one dust bin and let me search for it (I assume this is his methodology since he used an .rar file).

On top of that, an iPad does not open .rar and my new laptop does not open .rar without a new app - I am not going to install a new app just to look in this guy's dust bin.
I haven't needed .rar files since I was doing tape backups of a network of Sun & Silicon Graphics workstations back in the mid-1990s. I don't see the app being a benefit after this thread dies.

 

Look at the Fluke project here: http://vondervotteimittiss.com/belfry/

I ran into it when searching the vast internet.

But, the voltage you want may be in the instrument.