Macbook Pro power adapters and signal voltage

Hi all
I'm looking for fairly technical details about how a Macbook interacts with it's power adapter.
My theory:
If wikipedia is anything to go by,  when a Macbook power adapter is "on" but there is on load (no place to the send power, a.k.a the adapter is not connected to a device or the device isn't excepting power) the power adapter produces a single voltage of 6.86 volts (a fraction of the 16.5v or the 18.5v that is possible) that can inform a Macbook that a power adapter is available to draw from.
http://en.wikipedia.org/wiki/MagSafe#Pinout
From further observations of my Macbook Pro the charge indicator LED on the magsafe connector, when the power adapter is connected and the signal voltage is established as available, the power management within the Macbook Pro "thinks" for a moment and decides how much power it should draw from the power adapter.
The issue:
I figure that my theory is well reasoned but will more proof before I considered any off it fact.
The most direct way to confirm my theory is to cut up a Macbook pro adapter and start testing. Yet getting and modifying a Macbook adapter to be a test subject costs time and money and asking the web for answers is cheaper on both accounts.
Questions:
Macbook adapters produced fixed voltages? Either signal voltage (6.86v ?) or operating voltage (18.5v or 16.5v depending on adapter model)? They don't produced a range of voltages?
Is the signal voltage really 6.86 volts? How many amps or milliamps of signal voltage is needed from the power adapter for the Macbook to consider the adapter as "good" to draw from?
Allen

Shouldn't cause any problems. The main issue will be that the 60w adapter won't provide enough juice to both charge the MBP battery and run it if there is much of a load so I'd avoid using the 60w on the MBP for anything other than charging the battery whilst not using the machine - sudden power shortage could be painful for the machine.
Best of luck.

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