My LM324 Will not invert a voltage signal...why?

Question

I am using an LM324 quad op-amp to attempt to invert a signal. I followed the set up exactly...2 resisters...one from the signal and one doing feedback from (v- to vout).

My ground is 0 (pin 11) and my Vcc is +5 (pin 4). My input signal runs through a resister then converges with the feedback resistor into pin (2). The v+ pin connects directly to ground (pin 3). Finally the output voltage sends a feedback and passes the voltage out of the system (via pin 1).

I dont understand why my signal is NOT inverting. Why would pin 11 suggest a different value than ground? I realize some op amps need both a +5 and a -5 voltages to operate, but this one does not ask for that. Does that mean this IC cannot possible invert a signal?

Also...i realize that although the signal comming in will be +/- 5V...the signal out will be reduced to approximately -/+4V due to the op amp limitations.

How can I fix this inversion problem?

Answer 1

pin 11 has to be tied to -5V (with respect to ground) -- not ground, itself.

Because it is tied to ground that limits the negative swing of the OpAmp to 0 volts (slightly higher, actually).  To get a negative output voltage, you need a negative power supply voltage.

.

Answer 2

Your op-amp can only give an output that is within its supply voltage range (less some losses).  

So, if your supply is +5V and 0, the only outputs you can get are between +5V and 0.

Answer 3

the outputs and inputs can not go below ground.

Read the data sheet.

Move pin 11 to -5v and you will be OK.