Photovore robot
The 26th of march there was a art festival based around technology
called STRP in eindhoven. There
would be all kinds of robots and high tech artworks there that where
all interactive. That was a lot of fun offcourse but my page is mostly
about projects. At the festival there was also a small robot workshop
where you could build your own "photovore" robot for about 3 euro's.
You get a baggy with parts, instructions, a solar cell panel, a motor,
some steel wire and some bits like plastic tubing and beads/
After waiting in line for about half a hour it was time for assembly!
Well i still need to get the assembly photo's...
But after a while i got the following result:
But offcourse i need to modify it. Why? Well, if it aint broken, fix it
until it is!
Anyhow, i went on putting in a higher capacity capacitor of
4700µF instead of the current 2200. This way it could deliver
more power and could get unstuck from simple grains of solder that
where on my worktable or i could let it ride around in the round cap of
a container.
But i wasnt satisfied, when the robot is in direct sunlight it works
fine but it will barely run under a desk lamp. Offcourse brightness is
the problem, but it was not charging up properly, power was leaking
away. The green led is a blinking led type. You can see it come up
flashing when it is almost ready to fire. But when it starts to flash
it eats up power so the voltage never reaches the firing level. So it
is eating up precious power.
Time for a redesign. After identifying the solar engine type of the original
robot i set out to find a more efficient one with a lower quiscent
power usage. I was set on this
solar engine, no fiddling with pot meters as a LED would provide the
voltage reference to fire. After breadboarding a prototype to check its
function it worked quite well with a red led as a load. So i set out on
making the engine on a small circuit board, and attach it where the old
solar engine was.
Below you can see the result:
It works much better now, with less ambient light it will just move
around less. It has a much lower quiscent power use so not too much
energy will leak away. I have not measured it directly but it has to be
less then the original as it moves around a lot more. I still have to
test it in the sun but i think it will work just as well in the sun as
out of it. I used discrete transistors as i did not have equivalent SMT
parts for these, most of the resistors are SMT except for the 1 Mohm
resistor.
I really like these small solar panels, they are small and robust, but
quite expensive on ebay. I asked one of the people that where on the
robot workshop where they got their panels in bulk. But the person
didnt know. Too bad, i could have used these for projects.
SMD photovore robot
I have rebuilt my photovore robot as a test case for my PCB drawing and
etching, it has been greatly improved in efficiency and size as you can
see below:
Closeup:
Below you see the second PCB I made, the led has been soldered in but
the rest needs to be done. The led itself is in 1206 case, the
resistors are all 0805 size components.
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Last update at: 26-04-2008