Opamp on +9/-9 bipolar supply ?

[ubaid88]

Let say if there is circuit which originally works on +9v supply(battery). Now i want to make it to work on 9v bi-polar supply. So now i must convert +v/2 nodes to Gnd and connect +9v on pin8 and -9v on pin 4, rite? Correct me if iam wrong. You are also welcome to make any further suggestion.

Thanks in advance .

[daverdave]

I think it depends on the circuit, but yeah, basically you'd have the opamp power supplies at +9 and -9 and then the Vbias at ground. This means that the voltage swing would be between +9V, 0V and -9V as opposed to +9V, bias (4.5V say) and 0V.
Not sure if you'd need any other components for better reliability, i know that some parts may not be required, such as DC blocking caps on the outputs perhaps, although they might be better left in the circuit just to make sure DC is filtered out.

[ubaid88]

Thanks for reply.

wat you could say on this circuit?

[daverdave]

Hmmm, I'm not too sure. I'd say that you could run it with a dual supply but you'd probably need some component changes to accommodate a bipolar power supply. Remeber that the peak to peak voltage will be higher, 18V as opposed to 9V so that will have some affect to the circuit I'd imagine. You'd be better seeing if one of the more experienced guys will chirp in. it's an eq circuit right?

[ubaid88]

yeah preamp+active eq.

[daverdave]

Yeah, I'd imagin some tinkering with the resistor values in the non-inverting opamp stages is needed for the best amplification. Not too sure whether the caps need any attention or not. I don't think the cap values in the actual filter stages would make a difference but I could be wrong, the resistors might. Again, someone with more experience could help out better.

[ubaid88]

Anyway thanks for your help uptill here

[PRR]

Why did you change the Volume pot to 50K??

It wants to be much-less than the 22K into the next stage. I think I proposed 10K pot.

[amptramp]

It looks like some of the electrolytic capacitors that would not have a problem (or as much of a problem) with a 9 volt supply would have to be bipolar capacitors for this circuit.  Some capacitors will have positive then negative bias on them on each signal cycle.  You can get away with this for a little while with the normal unipolar capacitors, but the capacitors will eventually fail.  You can get bidirectional electrolytic capacitors and I have used them in guitar amps (where the designer should have known better) to clear a fault in a tremolo circuit where capacitors were being driven in alternate polarities.

[ubaid88]

Why did you change the Volume pot to 50K??

It wants to be much-less than the 22K into the next stage. I think I proposed 10K pot.

Sorry it is just a mistake in da schem. Do you think Circuit is Ok, other than this?