Re: Buffer circuits?


"Charles Schuler" <charleschuler@xxxxxxxxxxx> wrote in message
news:O8idndFvXbW1vDreRVn-pQ@xxxxxxxxxxxxxx
>
> "Ron J" <bigschlong@xxxxxxxxx> wrote in message
> news:1135017657.158177.274780@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> All,
>>
>> Merry Christmas and a Happy New Year!
>>
>> I was looking through some sensors on Digikey. Some of the ratings are
>> given at a certain load. For instance, 50 mV at 1 k-ohm. If I wanted to
>> bump this voltage a bit higher, can I use the following op amp buffer
>> ckt?
>>
>> The sensor output is connected to 1 k-ohm resistor with one resistor
>> terminal connected to the non-inverting op amp input and the other
>> terminal is grounded. The opamp output is looped back to the inverting
>> input using a low loss piece of wire. The opamp output is then
>> connected to my measurement device.
>>
>> Will this type of circuit work accurately with little deviation from
>> the original voltage input at the opamp?
>>
>> I was thinking of all the losses that is encountered from the input of
>> the opamp to its output. My main concern is that since the output
>> deviation of the sensor only goes up to 50 mV at 1k-ohm, then noise
>> might affect it significantly compared to a higher output voltage,
>> right?
>
> Well, you said you wanted some gain, so why not use a 10 k ohm feedback
> resistor instead of a piece of wire? That would give you a voltage gain
> of 10. The non-inverting op-amp input is often grounded through a
> resistance equal to the parallel equivalent of the input and feedback
> resistors (to minimize offset error).

I should have mentioned that the signal is fed to the inverting input with a
1 k ohm resistor.


.

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