Making
A
Robot
Page 6
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FRED
Photopopper
Some constructors have found very low-cost ways of producing a very
effective Solar Powered wheeled vehicles.
One excellent article (there are lots of excellent articles) has been
produced by Ben Hitchcock. It is called
FRED.
It is a Photopopper using low-cost components. It uses two red or green
flashing LEDs to turn the circuit on when the voltage across the electrolytic
has reached about 2.7v.
The interesting part of the circuit is the two flashing LEDs. They change characteristics
according to the level of the surrounding light and this turns the circuit into
phototropic.
Below is a photo of the Robot. Click to read the FRED
article.
The Schematic for FRED: The
secret to the success of this circuit is the addition of a 220n and 3k3 around
the flashing LED. This is the cheapest and best circuit for a Photopopper.
The only problem is the slight random activation due to the flashing LED. But this adds to the realism
and creates unusual results. A circuit using a 1381 voltage-detecting chip is
more uniform in operation. Some flashing LEDs detect light and this
creates a phototropic effect. When the flashing LED detects light,
the trigger voltage increases. You must make sure the solar panel is capable of
delivering this extra voltage, otherwise the circuit will "lock-up." Now you have the best
circuit. You
can produce lots of different designs for a light-seeking robot.
Here are some photos from Andy's
Page:
Note:
Some bugs are named
with their present owner
40 More
solar-bugs!!
Andy's
links page will get you into hundreds of pages of Robots of all
descriptions.
This is only the start to an amazing world of "getting things to
move."
There is only one more thing to help you produce a fantastic new design.
It's a circuit to convert ANY voltage from a set of solar cells to a useable
voltage. This means you can use as few as 2 or 3 cells and get almost any circuit to
work . . . you don't have to buy an expensive solar panel! It's a voltage step-up
circuit. See it on the next page . . . P1
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