Using external comparator instead of the one in atmega

Hello.
First, apologizes for my English.

Here's the deal:
I made very simple circuit which is using analog comparator in atmega8. There is Ultrasonic receiver plugged into comparator. When it measure some vibrations, it makes very tiny wave and comparator tells me when it passes zero point.

It is in attachment,

I saw circuits where there were many operation amplifiers between ultrasonic receiver and atmega but I have to do it this way and i know it works because it works

Anyway I can't use atmega's analog comparator any longer because of some reasons and i figured out that I will use external comparator. So I made the same exactly circuit with LM311 Comparator but it doesn't work :/ Of course i gave there pullup.
There is always 0 on comparator output.

I think that atmega's comparator might be more sensitive than LM311. Anyway tell me, what to do?

The LM311 doesn't work with the input voltage at ground. To use it you would need a -ve supply as well to the LM311

There are many other op-amps that will work with the input voltages at ground.

Ok thank you for this help.
I am lame at electronics so forgive me
Anyway can you tell me what comparator would be good for me? I would prefer comparator. I know that I can make comaprator from simple op-amp but as i said I don't do electronics so I rather buy a whole comparator.

Using an op-amp as a comparator doesn't need any extra components.

Someone recently suggested this one https://focus.ti.com/lit/ds/symlink/tlv2401.pdf and that should be fine.

Thanks. In my country google gives only one match for search "TLV2401" or TLV2402" or "TLV2404" so are there any mor popular op-amps or any replacments for this? Cause I can't buy this in my country.

You might also try an OPA340PA (BURR-BROWN) with an 8-pin DIL package, a precision low supply voltage rail to rail operational amplifier wired as comparator.

For dual channel use OPA2340PA.

Boncuk

Ok Thanks. It is also hard to get here What do you think about TL074? I found someone told someone that it is simmilar. Can I use it?