DVM??

[eie]

how is the operation of a dual-ramp DVM?
and
what difference between a counter-ramp DVM and a dual-ramp DVM??


thanks~ ??? ??? ??? ??? ??? ??? ??? ???

 

[Kevin Weddle]

A digital voltmeter has to convert the voltage of the signal to a binary represention for digital readout. This requires an A/D. So a dual ramp A/D uses one ramp that takes the voltage higher and another ramp which lowers the voltage. This is how you create a time difference, by taking the voltage higher then low. A counter then counts the time back to the low voltage. How high the voltage of the signal is determines how high the ramp will take it. The negative ramp pulls the voltage past down the reference voltage. This is how it works.

 

[eie]

thanks kevin

then
what difference between a counter-ramp DVM and a dual-ramp DVM??

thanks!!

 

[Kevin Weddle]

There is very little difference between the dual slope and the single slope. Both methods are good and even the single slope requires two ramps. I chose a project with the dual slope because I could set the reference voltage at ground potential. It is not often hard to conceptualize the problems with setting a reference voltage. Whenever you have a regulated reference voltage your okay. If you must set the reference through a resistor it will change with the current thus creating a signal. So I would prefer the solid ground as my reference.

 

[eie]

thank you very much, kevin
could u mind giving some books' names or websites about these topic because i would like to know more detail?

thanks

 

[boose1874]

push...
I have the same question too...
does any body have some reference BOOK or Website???
please help ....thanks

 

[EdwardM]

Hi All

you could start your websearch at Analog Devices http://www.analog.com/en/cat/0,2878,760,00.html

Best of Luck

Ed