Shiva wrote:
[...]
I really wasn't that serious about
*my* idea - i just thought, hey, any bi-state -used transistor could
*reliably offer 3 states*, but, other than the fact that i could not
instantly think of easy (simple) ways to do the basics, it suddenly dawned
on me: The *heat* would be astronomical! Transistor off - 9theoretically)
inf R, no power to dis. Transistor on - 0R, once again, no power across it
(theoretically). but that *inbetween* state is where things start to
cook... you've suddenly got an R, and, for those of us who can't spell,
that spells "troble...
Of course, i'm making a huge assumption that you're in some way
interested, rather than spamming...
-dim

There's another way, already extensively in use in what's called -
appropriately enough - "tri-state logic." This has three output states;
ON (e.g. pull high), OFF (e.g. pull low) and DON'T CARE (floating). The
difference is that the ON and OFF states are both low impedance, whereas
the DON'T CARE state is high impedance. Its usage is generally simply to
allow the gate (or other device) to "drop out of the picture" when not
needed.

It would be possible for external circuitry to sense that third state,
however, for instance by applying a brief pulse.

But is there a benefit?

Cheers,
Fred