gEDA-user: another I/O port idea

[John Luciani]

On 9/21/06, DJ Delorie <dj at delorie.com> wrote:
>
> Been thinking about what it would take to convert to all 3.3v (outside
> the last stage I/O drivers) in the furnace project.  I was thinking
> how hard it would be to get mosfets with a small enough Vgs for my
> last I/O port plan (Vgs would need to be less than 1v) when it
> occurred to me that I can use the high Vgs to my advantage.
>
> Checking a few random mosfets, it looks like turn-on starts around
> 1.5v and really kicks in around 2v.  2v is more than half of 3.3v, we
> just need a little more drop to keep the 1.5v above it also.  Consider
> this schematic:

Why couldn't you replace the diodes with shorts and use BJT's rather than
MOSFETs?

(* jcl *)

-- 
http://www.luciani.org