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Isn't that obvious?why is the inverting amplifier not working?
Hi,
But the Opamp in most of your cases is overdriven.
There are many Opamp circuit tutorials, even videos in the internet.
Use them, they are for free. You urgently need to learn basics on your own. A forum can't replace school.
Also there are free simulator tools.
Then you can play around, measure every voltage and current without time consuming soldering.
*****
Let's just calculate through one example. Let's take the 1000 ohms, 1000 ohms resistors.
* supply voltage is 7.79V (this violates your Opamp's specifications, because it should be at least 8V. --> see "Operating Voltage" )
* voltage at +IN node is 0V (this means that this input is connected to a supply rail. This violates your Opamp's specification, because your's is no Rail-to-rail input type.--> see "Input Common Mode Voltage Range")
But let's assume from here on you use a suitable Opamp:
* Rf = 1000 Ohms
* Rin = 1000 Ohms
* V_inp = input voltage is = (V_ Rin - V_+In) = 1.45V - 0V = 1.45V
--> A = gain = - Rf / Rin = - 1000 Ohms / 1000 Ohms = -1
The expectable V_out = V_+In + gain × V_inp = 0V + (-1) × 1.45V = -1.45V.
( This violates your Opamp's specification. --> see "Maximum Output Voltage Swing")
-1.45V is beyound your supply rails. No opamp can output voltage beyond it's supply rails.
--> thus it is expected to saturate close to negative rail.
You may simplify your life with using eXcel for such calculations.
Klaus
Then I'm unusual, too ;-)For me, circuits are 90% reading and calculations and 10% doing - I don't think I am unusual.
Just to clarify:Read absolute max ratings
data sheet page 2:
Read absolute max ratings
read note 1
maximum supply voltage is +/- 18V to power supply pins
+/- 4V is the smallest supply voltage the op amp will operate according to specifications
Maximum signal input voltage +- 15V - to inverting and noninverting inputs
but if supply is less than +/- 15V , the signal inputs are limited to the supply voltage
data sheet page 2:
Read absolute max ratings
read note 1
maximum supply voltage is +/- 18V to power supply pins
+/- 4V is the smallest supply voltage the op amp will operate according to specifications
Maximum signal input voltage +- 15V - to inverting and noninverting inputs
but if supply is less than +/- 15V , the signal inputs are limited to the supply voltage