hey guys need help about adc/comparator

Thread Starter

mejiqon

Joined Jan 25, 2024
5
1. i dont get why you need vref in adc if you can convert the voltage to digital by resistors ..i mean, lets say 2.5 voltage enter v(in) and you have a chain of resistors,
each resistor go up by 1, then the third resistor dont have output and one before have output, and you get digital output, just it, why the hell you need vref if you can know like this...what the volatge????

2. i search the entire internet about the circuit of comperator, and hell nobody can provide clear answer, beside a tringler with 2 inputs and one output.. so i start to think my self that the only way comperator can compare 2 volatges is to have 2 resistors inside... one for v(ref) and one for v(in)
and if there is output, then its mean that the v(in) is bigger...because the volatge is bigger then the resistor and output 1...i found design of comperator from toshiba which have 2 resistors inside...

thanks
 

sghioto

Joined Dec 31, 2017
5,420
1. i dont get why you need vref in adc if you can convert the voltage to digital by resistors ..i mean, lets say 2.5 voltage enter v(in) and you have a chain of resistors,
each resistor go up by 1, then the third resistor dont have output and one before have output, and you get digital output, just it, why the hell you need vref if you can know like this...what the volatge????
Show in a schematic this chain of resistors to convert voltage to digital.
 

MrChips

Joined Oct 2, 2009
30,935
Think about this.

1706220835729.png

A 1-bit ADC outputs a 0 or 1 depending on if the input is above or below a threshold voltage.
How do we define the value of the threshold voltage?
 

Thread Starter

mejiqon

Joined Jan 25, 2024
5
Show in a schematic this chain of resistors to convert voltage to digital.

it will take time to make it in paint...
so i will do my best as i can

we have v(ref) and v(in) --> both of them go to a comperator...then the comperators go to xor gates...from there its run to the memory.
imagine you dont have v(ref) and only v(in) that go through chain of resistors from up to down and this resistors connected to the xor gates..now

lets say the volatge in v(in) is 2.7
so the first resistor is 1 volatge and suck in, and the rest 1.7 is flow to the xor gate
the second resistor is 2 volatge and suck in, and the rest 0.7 is flow to the xor gate
the third resistor is 3 volatge and suck in, and no output...

you get binary results from the xor gates
 

Thread Starter

mejiqon

Joined Jan 25, 2024
5
it will take time to make it in paint...
so i will do my best as i can

we have v(ref) and v(in) --> both of them go to a comperator...then the comperators go to xor gates...from there its run to the memory.
imagine you dont have v(ref) and only v(in) that go through chain of resistors from up to down and this resistors connected to the xor gates..now

lets say the volatge in v(in) is 2.7
so the first resistor is 1 volatge and suck in, and the rest 1.7 is flow to the xor gate
the second resistor is 2 volatge and suck in, and the rest 0.7 is flow to the xor gate
the third resistor is 3 volatge and suck in, and no output...

you get binary results from the xor gates
i mean by this you know that the voltage that eneter is between 2 and 3 by the resistors them self without v(ref)...only by v(in)

the problem is the most upper resistor will trick you as lets say the last resistor is suck in 7 voltage and you got in the v(in) 9 volatge , then you have here noise, not clear siginal or output...because its not in between
 

MisterBill2

Joined Jan 23, 2018
18,970
NO, you can not convert voltage to digital with only resistors.
And a comparator is a lot like an Operational amplifier but without feedback. So get an electronic text book and learn about what those devices do.
And is this really correct: About : Occupation Electrical Engineer ????

I have a hard time thinking it is. Not meaning to be nasty, just wondering because the questions were rather basic.
 

crutschow

Joined Mar 14, 2008
34,682
i dont get why you need vref in adc if you can convert the voltage to digital by resistors ..i mean, lets say 2.5 voltage enter v(in) and you have a chain of resistors,
If you don't have a reference voltage than how will the comparators that generate the digital output know when to change states at a particular voltage/
All resistors can do is reduce the voltage.

And I don't think hell has anything to do with it. :oops:
 

MisterBill2

Joined Jan 23, 2018
18,970
If you don't have a reference voltage than how will the comparators that generate the digital output know when to change states at a particular voltage/
All resistors can do is reduce the voltage.

And I don't think hell has anything to do with it. :oops:
"C" is exactly correct. By definition, a comparator must have two quantities to compare And until you understand how something works it does not make any sense to argue about how it works.
 

Thread Starter

mejiqon

Joined Jan 25, 2024
5
If you don't have a reference voltage than how will the comparators that generate the digital output know when to change states at a particular voltage/
All resistors can do is reduce the voltage.

And I don't think hell has anything to do with it. :oops:

you are wrong that resisitor can only reduse voltage it first , ask this any true electrical engineer and you will say to you you far awa from the ball park what resistors do...you can output a binary number with resistors and much more, its done...ask any real electrical engineer...he will say you are wrong..

second i dont need to grab any electronics books as i hacked the most complicated system on earth,, and few did it live on facebook...

now to the joke, people on the web think they are electrical engineers...and the entire web cannot simple answer how comperator build inside...we and other people checked it,, toshiba have comperator with 2 resistors inisde..
 

Thread Starter

mejiqon

Joined Jan 25, 2024
5
NO, you can not convert voltage to digital with only resistors.
And a comparator is a lot like an Operational amplifier but without feedback. So get an electronic text book and learn about what those devices do.
And is this really correct: About : Occupation Electrical Engineer ????
.. because the questions were rather basic.
you are wrong just it...
 

MisterBill2

Joined Jan 23, 2018
18,970
OK, and if you saw it on the cartoon channel I have no doubt that it was faked.
AND a whole of of folks will really appreciate an explanation of how to provide a comparator function with resistors and no reference voltage. It will be an education for many folks here, we missed it before.

AND, ALSO, given that your "information" states: About : Occupation Electrical Engineer , how can you present that you actually believe that fable you saw???? If you are an EE then what school did you go to for your degree???
 

crutschow

Joined Mar 14, 2008
34,682
ask this any true electrical engineer
I have a BS degree in EE from the University of Wisconsin, and 40+ years in the industry doing electronic design for advanced military systems, so I think I fit the definition of a "true electrical engineer". :rolleyes:
So I asked myself, "Is what I said true?" and the answer came back "Yes".

But you seem to think you're the expert (hacked the most complicated system on earth(?)) , so I'm not wasting my time in further answering questions from someone who is both obtuse and condescending.
 
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MisterBill2

Joined Jan 23, 2018
18,970
I am still waiting for that explanation about how to convert a voltage to digital with only resistors. The words in post #3 make no sense, so we need a more detailed explanation.
AND a resistor will produce a voltage drop across itself whenever a current passes through that resistor.
V=I (current) multiplied by R(resistance) That is Ohms Law and in fact sometimes it IS inconvenient but it is also one of those laws that does not get broken.
Besides that, I also am an electrical/electronic engineer, Graduated from Lawrence Institute of Technology, with 45 years of experience designing all sorts of electronic test systems, mostly for auto companies and their suppliers. And those folks are very picky about things must work perfectly all the time. And our products did.

So don't bother with a picture, just explain it to us with words. Many of us are rather good at visualizing what is described.
 

MisterBill2

Joined Jan 23, 2018
18,970
And as for figuring out how a comparator works, I look at the published circuit and follow how it works and it becomes rather clear what is happening. But when you even spell it so very wrong, no wonder the search tools could not locate the keyword.
AND, once again, those fakes on the cartoon channel know less electronics
 
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