Some circuit I have come across cut off the ground pin of regulators, why would a circuit not want a regulator ground pin to be used? any reasons why

 

The center pin is often connected to the tab:


Is that what you are calling the "ground" pin? What regulator are you using?

Cutting the center pin off and using the tab is just an alternative way to connect.

John

 

Regulator chips
AMS1117
LD33
FA22
LD1117A
D113EE
D112FB
AME1084

Cutting the center pin off and using the tab is just an alternative way to connect.

Why would they want to use the tab instead of the center pin?

 

Some regulators center pin is V out and other regulators center pin is Ground

How can you use the same circuit and just change regulator that has a center pin as V out and use a regulator that has a center pin as ground?

It won't work, but what would you have to do to the circuit to so you can use either types of regulator pin configurations?

 

Regulator chips

Why would they want to use the tab instead of the center pin?

Another reason is to make more room around the now 2 pin connection, less cluttered.

 

because the regulator would fit in a to3 socket that way.

 

Yes the regulator will fit in a 3 pin socket but the center pin is either a V out or Ground pin

I can't take a regulator that has a center pin V out and replace it with a regulator with a center pin that is a ground pin
Is there a way to use either types of regulators without modifying the PCB board?

The Tab is either ground or V out

 

I can't take a regulator that has a center pin V out and replace it with a regulator with a center pin that is a ground pin
Is there a way to use either types of regulators without modifying the PCB board?

You answered your own question, then typed the question.
You can't replace a regulator with a different pinout without changing the circuit board it connects to.

 

Some regulators center pin is V out and other regulators center pin is Ground

How can you use the same circuit and just change regulator that has a center pin as V out and use a regulator that has a center pin as ground?

?

Use a TO220 insulating kit and hand wire any pins that don't match the pad layout.