Ive breadboard this LM311 comparator circuit but it does not seem to behave correctly, or at least how the simulations behave in multisim.

 

You need positive feedback in order to add hysteresis in a comparator circuit.

 

Sorry I realised I was too eager to post this thread before trying out a few things. My mistake!

 

Is the scope display part of multism or is it a real live waveform?
I would expect the output to go high when the input waveform goes higher than 0.763 volts. That is not happening on the display. The very small amount of negative feedback will just make the rise and fall times of the output a bit slower.
Keith

 

You're violating the input voltage range spec:



With GND as the negative supply, the input voltage can't be below 0.5V. You need to use an opamp a comparator like LM393 that includes ground in the input voltage range when operated from a single supply.

When you go outside of the input voltage range, comparators can invert their output.

EDIT: corrected description of LM393; obviously not an opamp...

 

Is the scope display part of multism or is it a real live waveform?
I would expect the output to go high when the input waveform goes higher than 0.763 volts. That is not happening on the display.
Keith

Sorry Keith that is from the multisim oscilloscope, I've attached the circuit change I have made and the real live waveform.

 

I've attached the circuit change I have made and the real live waveform.

Can you include the input waveform?

I think the simulation was showing you inversion when you exceeded the input voltage range.

EDIT:
For the input in green boxes, the comparator is experiencing inversion bcause the input is below the allowable input voltage:

 

You can see by your displayed waveform that the comparator is oscillating as it switches. You do need some positive feedback as Mr. Chips stated in reply #2. See the attached datasheet application notes.
You are exceeding the input negative limit as Dennis pointed out in posting #5. You can get away with that as long as the signal source has a high impedance but that will increase the chances of the output oscillating. A sustained low impedance source on thre input, negative of the negative supply will damage the chip.
Keith

http://www.ti.com/lit/ds/symlink/lm311-n.pdf

 

it may also be that smoothing your divider with capacitor cuts off the Vcc voltage drop from +inp at the output transition
there are 2 ways to this -- split your 10k in voltage divider to 5k:5k ~ac ground with cap from in between -or- ~ac ground with cap from in between 1k8:10k and add resistor from there to +inp (keeping the 100k at +inp)