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Opamp DC offset
Opamp DC offset
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Old 21st May 2003, 06:04 PM   #1
jnxw2 is offline jnxw2
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Default Opamp DC offset

As a simple project I decided to so a simple preamp using high speed unity gain opamps as line drivers. One channel seems to work fine but on the other one there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct, can anyone think of what the problem might be? Could it be that the chip is somehow damaged?


Any suggestions greatly appreciated


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Old 21st May 2003, 06:44 PM   #2
Tube_Dude is offline Tube_Dude  Portugal
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Default The 7 volts ofset issue...

Quote:
there is a DC offset of about +7V on the +Vin pin, Im sure the wiring is correct,
Are you sure that this 7 volts are not in the source that is driving the + Vin pin?

If not...
Quote:
Could it be that the chip is somehow damaged?
yes...that's possible...

Cheers
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Old 21st May 2003, 07:06 PM   #3
jnxw2 is offline jnxw2
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Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input.
Also dont know if it is important or not but it is a current feedback opamp


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Old 21st May 2003, 07:28 PM   #4
Tube_Dude is offline Tube_Dude  Portugal
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Quote:
Sorry my mistake for not being clear enough, the DC Offset is on the non inverting input
And the inverting input is at 0 Volts?
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Old 21st May 2003, 07:41 PM   #5
jnxw2 is offline jnxw2
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Thats right, the inverting input is at 0V as is output.


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Old 21st May 2003, 07:45 PM   #6
jan.didden is offline jan.didden  Europe
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Default dc offset

We are really groping around in the dark here. A schematic (even rudimentary, hand drawn) would help YOU immensely.

Jan Didden
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Old 21st May 2003, 07:47 PM   #7
Tube_Dude is offline Tube_Dude  Portugal
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Default The dead Ic...

Sorry...bad news...the Ic is dead!

It will rest in peace!!!

Amen!
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Old 21st May 2003, 07:53 PM   #8
jan.didden is offline jan.didden  Europe
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Default offset

Not to spoil your party, but how do you rate the chance that the new opamp you put in will also die untimely? Where's the f<]u*#c*#k@i^%n@!g schematic??

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Old 21st May 2003, 08:15 PM   #9
jnxw2 is offline jnxw2
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Yeah i was kind of coming to that conclusion aswell

Here is the diagram.

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Old 22nd May 2003, 08:01 AM   #10
Werner is offline Werner  Europe
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You connected the - input to ground???
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