Regulate or not?

[codan]

Hi Everybody,

I have a simple opamp circuit that has been running on a 9v battery very nicely, i want to change it to 12v as i have some rechargable 12v batteries now.

My question is that my batteries are 12v 1800mAhrs, is it possible my circuit could draw a lot more current from these batteries compared to the 9v batteries & fry something.
Or will the circuit only draw what is necessary & the same as before?

Do i need to regulate the voltage back to the original 9v or do i have to regulate the Amps Or just hook it up to the 12v battery.

One question turned into about a hundred--again.

Thanks

 

[crutschow]

Assuming the op amp can tolerate 12V and it's just a simple circuit then it should operate fine on 12V. It will draw no more current than it needs.

 

[codan]

Thanks crutschow,

I assumed it would be fine but it doesn't hurt to ask to make sure.

Thanks Again

 

[audioguru]

You can look on the datasheet for whichever opamp you are using.
The datasheet for the TL071 and TL081 opamps show that the supply current increases from 1.3mA when the total supply is 7V to 1.35mA when the total supply is 29V.

 

[codan]

Hi Audioguru,

Thanks for that, i have to admit i neglected to notice that on the data sheet.

Thanks Again.

 

[MikeMl]

Another point: if the bias for either of the opamp's inputs are derived from the 12V (e.g. a resistive voltage divider), then there will be a corresponding shift in the quiescent output voltage. If the bias is derived from a regulated voltage, then there will be only a slight shift. This is due to the opamp's Power Supply Rejection Ratio (PSRR), also listed on the spec sheet.