can I measure negative voltage(-5v to 5v) with ADC804? how?

[tictac]

adc and negative and voltage

Hi
can I measure negative voltage(-5v to 5v) with ADC804 and HOW ?
if it doesnt possible please tell me about some 8bit ADC to do that

by Regards.

 

[umery2k75]

Re: ADC0804 negative voltage

Yes, its possible.
But this would lower down the 8-bit resolution. You leave ref/2 pin open, don't connect it. If I remember that PIN number correctly, in this you get range from 0-5V.You first takes the absolute value of -5V to +5V, so altogether difference of 10V, means if you give negative voltage, it must be get convert into positive value, if you get positive value it remains the same, now suppose you get scale from 0V to +10V, 0V represents -5V and +10V represent +5V.Scale it down from 0-10V to 0-5V. Now then feed it into your ADC0804. All is done now.
Remember:
1)Add +5V in input, you get range from 0-10V.
2)Divide the range 0-10V with 2
3)Fed the result into ADC0804.

ADC0804, won't know what it means, you will be the one, who must understand what the values means.From 0-2.5V, this means range from -5V to 0V. From 2.5V to 5V means 0V to +5V

 

[tictac]

ADC0804 negative voltage

Hi umery2k75
thank you so much
can you tell me about add +5v in input? Can I do this with opamp?
and is there any ADC can measure negative voltage?please tell me about it?

Added after 8 minutes:

your reply was so perfect and good

 

[FvM]

ADC0804 negative voltage

There are plenty of ADC that measure negative voltage, but they need dual supply, generally.

ADC804 input can be scaled to +/-5 V by two resistors respectively a voltage divider to +5V. The method is discussed in the datasheet for +/-10V input.

 

[tictac]

Re: ADC0804 negative voltage

Hi
Is this circuit work correctly? vref pin=open

 

[FvM]

ADC0804 negative voltage

Yes.