Simple Applications with Opamps ~ Need Help

[Kaleen]

Hi everybody, I need help to make a circuit with opamps (LM311). I have in mind to make a basic voltmeter and use an Analog to Digital Converter (or a DAC if needed) to display the result of the measure in the voltmeter. But i have a big big problem :cry: ....I just don't know how to start.
If anybody can help me with a schematic diagram or anything i would really appreciate it :lol: , i must have to say that i'm almost new in this area of electronics and i barely understand opamps and their applications :shock: .
If i didn't make myself clear on what i'm trying to do please tell me or just say what you're thinking... :idea:

 

[nettron1000]

Similar thread here:

https://electro-tech-online.com/viewtopic.php?t=4244&start=0

 

[Roff]

Well, for starters, LM311 is not an op amp - it's a comparator. You can make an A/D converter with comparators combined with a lot of other parts. Are you doing this on your own, or is it a class assignment? Give us more information if you want help.

 

[crust]

As mentioned the LM311 is a comparator. However, I've built a system that used a PWM, low pass filter and compator to estimate the value of an analog input. It works well if you are measuring a slow signal with respect to the time constant of your low pass filter. On the small AVRs with a built-in comparator it is a nice way to measure battery voltage, etc of your designs.

 

[Kaleen]

answers

thanks everbody for your answers...Sorry, i didn't remembered it is a comparator (i suppose i have to use a 741..do i?)...and answering your question, yes, it's a class project but we have to decide what to do, so i thought it was a good project 'cause we were learning how a basic voltmeter works and how the adc's makes the conversion and i think it would be cool to make both work together but i don't know if it's possible to read the voltaje (with the voltmeter) and display it in 7-segments displays with the ADC...if anybody can help me answering i'll really appreciate it...