Problem with OP-AMP inverter

Thread Starter

Treivik

Joined Oct 15, 2019
1
I have a problem with building the op-amp inverter.
The CA3140E I am using worked fine for the not-invertering op-amp.

So my problem is:
When I apply +0.7V DC input the output is around -14V and continues to be around that until I switch the input signal to -V.
Then it works fine and the output will be the correct value (except it is +V).

Anyone who knows what the problem is?
 

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crutschow

Joined Mar 14, 2008
23,373
It's not the only thing in Spiceland that's confusing. For example, resistors are polarised.
If you are referring to current measurement through the resistor, how else would you specify the direction of current in a resistor that's less confusing to you?
 

Alec_t

Joined Sep 17, 2013
10,384
how else would you specify the direction of current in a resistor
Spice isn't helpful when it comes to determining the current direction in a circuit. Flip the resistor symbol through 180 and the current apparently reverses (because of the pin order of the symbol)!
SpiceConfusion.png
 
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