hello there...
I could use your help...
I need to make a voltmeter that measures max of 24 volts. For output to have 7-segment display.
If you have any ideas how to get this started or even a complete disign (same or similar specs) i really could appriciate it.

Thank you.

 

A/D converters with direct display drive output

http://www.microchip.com/1010/pline/...yadc/index.htm

example scematics are in the datasheets

 

thnx for the reply...
i ve seen the datasheets but there is not much for me there :shock:
i was wondering if you could be a bit more specific and explain the principle about how this is going to work...

Thank you

 

If you want to display a analog voltage on a display then you're going to need a Analog to digital (A/D) converter... A device that changes a analog voltage into a digital value for you to work with...

There are diffirent kinds of A/D's. Some offer a serial interface for a µController, others offer a parallel output and others are capable of directly driving a display...

The link i gave you are such devices... There should be scematics in the datasheets...

 

thanks for your reply for one more time....
but i already know that do you mean.
the problem that i have is that i cannot get an analogue singal at the first place, and i was wondering if you had any kind of idea to do that. an initial voltmeter design for instance!!

Anyway, thanks very much for your time!!xxx

 

i'm getting confused here...

You say you want to make a digital voltmeter; so i assume you want to measure a voltage....
The voltage you want to measure is the analog signal...

 

Well, lets ake this clear...
i need a battery energy mesurement system!!
I simple words... a voltmeter (digital is preffered), which is gonna be able to measure the battery (24V max) at any time and display this raeding in a 7 segment display.
i dont care whether the initial design is gonna be analog or whatever, the only thing that i need is a design to start with...
afterwards i can use a A/D converter to apply it to the display.

i hope this is clearer for you!! sorry for the misunderstanding

Thnaks

 

I think you are the one that doesn't understand

The A/D converter IS your voltmeter... Its all you need...
So if you look at the datasheet for the TC7106A
http://www.microchip.com/download/li...adc/21455b.pdf
page 3, you'll have your digital voltmeter scematic

 

ok you were right!!

sorry for the misunderstanding, but i didnt had a proper look at the specs!!

anyway, talk to you later

 

hello,
do you have any suggestions for a 48V or 24V meter???
:roll:

 

Add a voltage divider to get your input within scale

So for example, if you set your reference voltage to 100mV
and you divide your input by 1000 then the display will show 24.0 at 24V and 100.0 at 100V

Dividing is done with (precision) resistors .
For example if you add 2 resistors in series between Vin+ and Vin- with values 1K and 99K then in between you'll have a voltage divided by 100

 

you see, i'm troubled about what is writen in page 4 of the chip you mentioned, where it says as a note that "Input voltages may exceed the supply voltages, prodived the input current is limited to -/+ 100uA".

i want to measure voltage and current from 4 car batteries connected in series, summing to 48V, and i'll probably burn this chip.
do you know any way that i can reduce the current (which i believe it will be around 6~10A) to the current of the chip requires (some uA)?

thanks for your help and speedy response!

 

First of all - like i said in my previous post. You need to divide the voltage you measure with resistors. If you give the chip a reference of 1V and you divide your voltage by 100. The meter will read 48.0 when your voltage is 48V... Because of the division the chip actually only gets 0.48V
wich is safely below the supply voltage of max 15V

Secondly the input current of the chip and the current the to the device that is connected to the batteries have nothing to do with each other. The input current of the chip is influenced by the input voltage and the chips input resistance... It has nothing to do with the load you are driving.

 

Hi, this one is for Exo,

I've posted a reply on the topic by sofia, on how to work on a digital clock, I have 4 weeks for a class project, and I'm going to hand in several Ideas to my lecturer, the first are the digital clock, second maybe a combination lock (with no reality use at all, just accept and deny true/false codes), and I'm interested to know how to make a PIC16F84 base voltmeter, can it be more complicated than the other two?will implementing the program be difficult, I only know about assembly so far, and that isn't much too, just some simple LED programs, you know... the basic input output for PIC16F84

Or maybe you can give another Idea, I would appreciate it a lot, but I would appreciate any help at all actually :lol:

Thanks a lot

 

A digital voltmeter with a pic isn't that difficult. Find yourself a nice A/D converter. You can use all sorts of A/D's parallel outputs, serial outputs...

Parallel A/D's are easyer to program, but require more pins, serial versiond will do with a pin or 2 but require code to clock the serial data in.

Once you got your data displaying it on a 7-Segment or even a HD7780 LCD is no problem

Microchip itself has quite a range of A/D's and also example pic code on how to interface them
www.microchip.com

Other manufacturers like Analogdevices and national offer great devices too