How to check comparator

[giosif]

Hi,

I am trying to check if an LM393 dual comparator IC is healthy and I wanted to confirm whether the circuit I've been using for testing op-amps located at the link below could be used for comparators as well.
https://startingelectronics.org/beginners/circuits/op-amp-oscillator/

If I am to judge things from the data sheet of the LM393, it looks like I should be able to use that test circuit but, OTOH, since there seems to be a differentiation between op-amps and comparators, I am not 100% sure.

A quick search on the forum didn't reveal a similar topic.
Thanks!

[Doctorandus_P]

A lot of comparators can only sink current to GND, and not output a voltage.
Therefore you have to modify your circuit a bit.
Instead of connecting the led between the output and GND, put it between the positive supply rails and the output.
Aditionally, you might want to put another resistor parralel to the led to pull the output closer to the supply rails if the led is off.

[giosif]

That is most interesting and a very subtle difference (to me, anyway).
I've modified the circuit and I can see it oscillating now.
Thank you for that very useful piece of information!

I am suspecting the comparator is sinking current to GND when the inverting input is higher than the non-inverting one, right?