Negative Voltage vs Two Floating Supplies

[joegtp]

What are the advantages of using something like an LM337 to generate negative voltage verses building two floating supplies and hooking them up in series and using the center point as the ground reference (such as the Mastech HY3005F-3)?

[c4757p]

LM337 does not generate a negative voltage in the same way that LM317 does not generate a positive voltage.

[c4757p]

A device that does generate a negative voltage (like a buck-boost converter) has one huge advantage - you only need one DC power input.

[joegtp]

LM337 does not generate a negative voltage in the same way that LM317 does not generate a positive voltage.

Sorry. By generate I meant to say regulate.

[vlf3]

There is no problem doing that, so long as each of the two secondary windings of the transformer are independent and floating... however, any virtual ground DC, between each floating supply if made to a metal chassis, with a mains earth; should then be your common ground and interconnections for signal-screen-cable returns.

[Harvs]

There's no difference if you assume you're only ever going to need a positive and negative rail.

But I use my floating rails to generate different things all the time.  Some times I need two positive rails with a common ground, sometimes I need one rail to power the input to something, and another rail to float on top of some other point in the circuit that has no defined reference to the other rail.  It just adds flexibility.

Often this doesn't come from a circuit that would have that in normal operation once it's fully built, but rather, if you're trying out a concept and don't want to put hours into building a multi-rail  supply just to see if the concept is going to work.