Hey all.
I saw the thread "Dual or single supplies for opamps" - but there are no information about IN, so I need to ask u the question:
I have a ciruit as shown in the jpg image.
when known:
Vdc>0
V1<=Vdc
Vout>0
In the calculation I have -R1/R2*Vdc, but Vout always positive.
Can I conenct the amp to single power supply or I have connect it to the dual one.
please explane.
Whilst it's possible to use a virtual earth circuit and just one supply, all the signals comming into and out of the op-amp need to be referenced to the virtual earth.
You can make a virtual earth with another op-amp so you could use a dual op-amp like the TL082.
Since the circuit you show is a non-inverting amp with gain, you can use a single supply only if the op amp is capable of rail-to-rail input and output voltages. A standard op amp, such as a 741, will only operate to within a couple volts or so of the supply rails.