Topic: 6V vs. 9V vs. 12V

[bluevolvo]

Assuming the V3's Voltage Regulator outputs 5.5V:
- if you pass a V3 12 Volts the power circuit will run at about 45% effeciency
- if you pass a V3 6 Volts the power circuit will running at about 91% effeciency.
These numbers are not exact as the circuit it self draws power.

The lost power is converted to heat - so a V3 running on a 12V will run hotter than a V3 on a 6V.

Not entirely correct.  I can see where this could turn into some engineering topic...

ANY 78xx series Regulator (or other correctly engineered discrete transistor-resistor VR circuit) with "NO LOAD" is only going to draw whatever current is biasing the transistors in the circuit and some designed load (in the > ma range).  This is the effeciency and without knowing resistance you can't just divide ouput V by input V. There is not going to be [or if correctly engineered should not be] some enormous amount of energy or heat wasted here.  For sake of simplicity and further discussion let's accept this as nill at look specifically at 78xx series.

You can run 35V to these things.  Say I have the 2 700Ah batterys from my RAM 2500 Cummins powering a 7805 regulator.  Series "24V" at 700Ah or parallel "12V" at 1400Ah your pick (call me crazy and in reality it's more like 28.8 and 14.4).  If my load is OFF there is NO current so no waste and NO heat.  If I put a 5 Watt 5 Volt light bulb in the circuit I am going to draw 1 amp.  The 7805 is going to get hot and may thermally shutdown without some heatsinking, it is dissapating ONLY what the circuit is drawing, 1 Amp or 5 Watts.

1 Watt 5 Volt bulb = 200mA it's going to cruise along just fine for many many many days

sooo

The Zoom H4 runs on 2AA Batts.  2 NiMh batts put out about 2.4 volts.  The wally they give you says 9V but it puts out 14.4 at no load.  I run mine with a 7.2V RC pack.  The electrons are all happily going where they need to and the 414's get the same 45.7 volts phantom all 3 ways.  Life is good. 

Of course without looking at any particular OEM's circuit you never know what they did in there...

REFERENCE: http://www.national.com/ds/LM/LM7512C.pdf (plus OHMS LAW and 35 years of building do-dads and what-nots)