Homebrew PCBs

> On Fri, 08 Jul 2005 01:24:01 +0200, Tony Smith <ajsmith@...>
> wrote:
>
>>
>> Stefan doesn't care which way the paper hangs, so long as the dispenser
>> is
>> driven by a chicken grill motor.
>> Tony
>
>
> Would be way too slow for unrolling paper. I don't have that much time to
> waste on the loo.
>


Oh come on.  Add a few gears (left over from the old HP Laserjets, we know
you don't have any laminators :) ) to get the speed up.

Only problem is constant velocity, the paper will dispense faster as the
roll unwinds.  Oops, hang on, other way round.

You'll need some way to measure paper usage (bounce IR off the paper? 
ultrasonic?) so you can adjust the speed.  You need a PCB to mount the
electronics, but I figure you can sort that out.  Sounds like a job for a
PIC (or a PicAxe).

Web enable it so you can check the paper status before making the trip, or
to send you email before it runs out.  Automatically order from
www.ToiletPaperOnline.com?  Startup!  IPO!!  Oh, it's 2005, not 1997.

You can estimate the number of squares left, but that gets tricky as some
paper is thicker than others.  You need the paper to pass thru another
sensor to measure its thickness.  Knowing the thickness of the paper and
the size of the remaining roll you can calculate the number of squares
left.  Even that gets hard as the size of the squares varies, apparently
Europe has metric toilet paper.  (It's true, I tell ya, I read it on the
'net).

Hey, that actually solves the constant velocity problem.  The paper is
pulled out by rollers rather than just spinning the roll.  Make the
rollers big enough and you won't need to gear up the chicken motor.  Don't
need the PIC either, except to web enable it.

Another catch is the size of the cardboard inner tube varies, so you'll
need to measure that as well.

Add a IR pair to detect your hand waving in front of it (like hand dryers)
to dispense the paper and you're set (hmmm a gas sensor could ... ok never
mind!).

Tony