Very Computer

Hi all.

After seeing Dave on the Discovery Channel just before the new year I
went out and got all the parts I needed to build a solar engine.  I was
short the solar cell and no stores in my area had them.  I finally got a
hold of a broken solar calculator and last week I built the solar engine.

The problem: it doesn't work.  I have a really big solar cell, 6 inches square
and a smaller one from a calculator.  If I hook up either one the motor never
turns although in direct sunlight I can see the FLED actually blinking.
If I unhook the negative side of the capacitor and touch it to the positive
lead of the FLED the motor turns.  Any ideas as to why this isn't working?  
I've currently got this on a breadboard so any changes are easy to make.
I used the GIF from Dave's web site to construct the circuit.

TIA,
Ray

: Hi all.

: After seeing Dave on the Discovery Channel just before the new year I
: went out and got all the parts I needed to build a solar engine.  I was
: short the solar cell and no stores in my area had them.  I finally got a
: hold of a broken solar calculator and last week I built the solar engine.

: The problem: it doesn't work.  I have a really big solar cell, 6 inches square
: and a smaller one from a calculator.  If I hook up either one the motor never
: turns although in direct sunlight I can see the FLED actually blinking.
: If I unhook the negative side of the capacitor and touch it to the positive
: lead of the FLED the motor turns.  Any ideas as to why this isn't working?  
: I've currently got this on a breadboard so any changes are easy to make.
: I used the GIF from Dave's web site to construct the circuit.

  What is his sight?  I wouldn't mind building a solar engine myself.
Thanks...

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I just finished gathering all the components for the solar engine.  I lost the schematic however and I think Dave Hrnkiwd (sp?) took it off his site.  If there is another way for me to get it would you post the address?

Thanks,
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I believe its still there.. I think they did move it though so its not so
obvious what your clicking into.  Anyway, its under the link thats called
(I think this is it) Solar Engines..  uhhh.. now I cant remember the link
name.. the link that describes what 'they' are.  Its there, just search
for it.  Sorry I cant remember the exact link name.  Im going to have to
look for it now.. hehe.

Question: What do you guys do for parts?  Like say you want to make a
small car or something.  I guess you could get wheels and stuff from
remote control cars or something.  What about gears and stuff when you
want to design your own movable joints?  Just looking for tips and other
peoples ideas.  Also, Ive been wanting to make a solar engine with
collision avoidance circuitry.  I have the circuit designed, but my
problem comes to actually making the steering system.. Anyone know of a
fairly light weight method of making a solar robot turn?
Actually, one more question:  If you take that design for the solar engine
as mentioned in the posts here, if you took a bigger and bigger solar
cell, or even linked a few in series (or is it parallel?), would you get
more and longer lasting power from the robot.. Or does it just cut off at
some point?  I think the diagram says to use a 2V solar cell.. can you
increase this without changing the rest of the circuit?

---=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=---
Aaron Merifield
Carleton University
Graduated spring-95, B.Sc. Physics.
Department of Computer Mathematics, 3rd yr.
      *=--=-==-=--=-==-=--=-==-=--=-==-=--=-==-=--=-==-=--=-=*

WEB-PAGE:     http://chat.carleton.ca/~amerifie  (re-doing it!)
---=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=---

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The Embedded Control Experts:    http://www.amresearch.com

        Just saw the perfect Robotic power source at Costco last nite.  Siemens
has a portable flourescent lamp with one side just _covered_ with photovoltaics!
Only $20 and you get not only the cells but a battery, flourescent lamp and an
inverter too!!!

        Have fun, Albert

--
The Embedded Control Experts:    http://www.amresearch.com

Parts: I have a junk box, actually, more like a junk apartment ;)
from which I can find lots of broken stuff.  Even solid conductor
wire can be used for structural members on small Solar-Rollers.
Old tape decks / portable tape players / VCR's have tons of gears,
belts, pulleys, shafts, etc.  (Pinch-rollers!!!)
Broken or discarded kids toys are a great source of wheels.
A craft store near me has a section of stuff for people who like
to build stuff with popsicle sticks.  There are various shapes of
pre-cut popsicle-stick-like-wood, including three sizes of Solar-
Roller Wheels. (Okay, they called them wooden circles)

Steering:  Build two Solar-Rollers.  Join them side-by-side.  Tilt
the solar cells to the sides.  Watch it go.
While you are at it, read:

Title-   Vehicles: Experiments in Synthetic Psychology
Author-  Valentino Braitenberg
Publ-    The MIT Press

Interesting, and very applicable to solar-engined vehicles.

Extra cells:  If you add them in parallel, you might need diodes
in series with each to prevent more-active cells from charging
less-active cells. (You want them to charge the capacitor.)
If you get it set up just-so, you'll find the Solar-Roller moves
the same distance per charge, but more often.

Good Luck.
Richard

---------------------------------
Also Mark Tildens work is pretty interesting!  He has little park he calls
'Robot Juarasiac Park', it is a table in his office full of solar robots.
They are VERY cool and have no cpu's just transistors.

Here is his basic circuit design found posted:

Subject: Re: Solar cells and capacitors
Date: 3 Dec 91 15:01:39 GMT

Try this:
          |-------------------O-------------O-----------------|
          |                   |             |                 |
          |               |-------|         |                 |
          |               <  mot. >-        |               + |
          |               |-------|         |                ---
          p      2.2k-10k     |           + |              -------
           n|--O---/\/\/------O           -----  >2200uF     ---    >2v solar
          P    |              |           -----  cap       -------      cell.
          |    |              N           - |                ---
          |----|------------|p              |              -------
               |              n             |               - |
              /-/             |             |                 |
               ^ Zener        |             |                 |
               | mc4742       |             |                 |
               |--------------O-------------O-----------------|

Legend:
               |                      |
collector-     P                      N                      |
base-      -|n     PNP trans.     -|p      NPN trans.    ----O----  wire join.
emitter-       p                      n
               |                      |

Essentially it's a modified SCR design with supercritical feedback.  The
zener starts clamping at vcc-.7v and will eventually trigger the PNP,
triggering the NPN, and will lock so long as the motor is moving.  The
beauty of this design is it's incredible high impedance until tripped.
For transistors, I've used 3904s and 3906s, but for higher power designs,
the NPN must be replaced with something like cascaded 2n2222s, or high
gain power transistors, like TIP 31s.  The zener should be rated to trip
at 2 volts below your solar-cell voltage rating to get maximum power.

This circuit is called the BEAM solarengine.  I developed it for the
Robot Olympics, used to build a solaroller device which covers a 1
meter distance in pure sunlight using only a cell 2-1/2" by 1/2".  I
promote it in my BEAM robotics package because of it's simplicity
and cheapness of parts.  What's your application?
--------------------------------------------------
And there you go, I believe?
-Steve Walz