In PSPICE I created a circuit with a VDC = 6V feeding into a uA741 op-amp in a inverting amplifier configuration, with both the input and feedback resistors at 1K.
I expected Vout = -6V but instead got Vout to be about 0V. I also expected the V- to be 0V because of virtual ground but it came out about 1/2 of Vin.
I was wondering why the op-amp doesn't amplify at DC.
"zero" schrieb im Newsbeitrag news:M7P0e.36100$ snipped-for-privacy@twister.nyc.rr.com...
It does, but only in the given bounds. For the OPAmp to go to negative voltages, it has to be supplied with a negative voltage, which means that you have to use a symmetric power supply (two DC-sources in series, the connection point being ground).
So use
+6V | |----- --- | | | o--------+ | | | GND
----- --- | | | -6V
instead of
+6V | |----- --- | | | GND
and it will work. By the way, the 741 does reach its supply limits only within a margin of about 2..3V, so if supplied with +/-6V, you can only expect +/-4V at the output.
Paul
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