Re: ATM Advise, please...

[Dwight Elvey <elvey@hal.com>]

Donovan Buck <donovan@bravoz.com> wrote:
> >
> >          D1            D2
> >    |-----|>|-----x-----|>|-----|
> >    |             |             |
> >SC1 |     1.5 v.  |             |
> > ___|___   DC motor>           _|_ SC2
> >   ---             >          -----
> >    |              >            |
> >    |             |             |
> >    |_____________|_____________|
> >
> >

Hi
 Actually, this would work:

    |-------------x-------------|
    |             |             |
SC1 |     1.5 v.  |             |
 ___|___   DC motor>           _|_ SC2
   ---             >          -----
    |              >            |
    |             |             |
    |_____________|_____________|

 Solar cells are actually forward biased by solar energy.
This is why the voltage drops off when lightly loaded. As the
solar energy generates more electrons, and they are not shunted
off into another circuit, they just become forward junction current.
Using a solar cell in the dark, it would be forward
biased by applying voltage with the same polarity as
the normal output, reversing the current.
 This is also why, large arrays have protective bypass
diodes. If one cell in a series string had the light blocked or
shaded, the entire voltage of the array could be across
it backwards. Once it zeners, it can dissipate a lot
of power. This is avoided by bypassing every few cells
with a diode. This diode is normally back biased.
 It might also be more effective to have a large array
to collect energy and a couple of small cells to control
a H bridge on the motor. A mirror to redirect light in the
morning would make it so that it could self reset.
A two stage control system could be used that included
find adjustment using a lens to magnify.
Dwight