Elenco Green Projects - Manual (Page 34)

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Each power source has advantages and
limitations:
A. Batteries have lots of power but they only
store energy, they don’t actually produce it.
B. The hand crank has lots of power but only
while you are turning the crank.
C. The solar cell has limited power, and only
while it has light.
D. The windmill makes good power but only in
a strong wind.
E. The liquid energy source has very little
power.
Use the 5 power sources you
have set up in project 38 but
replace the meter with the clock
(T2) as shown. See if it works
with each power source (it
should). Take some notes in the
project 38 table - it has a column
for the clock.
You are not using the clock with
a separate energy storage
device, so notice how continuous
power is from each source (for
example, the clock stops when
you stop turning the hand crank).
Project #39
Powering Clock
Now replace the clock with the
horn (W1). See which power
sources it works with. Take some
notes in the project 38 table - it
has a column for the horn.
Project #40
Powering Horn
+
Now replace the horn with the
yellow LED (D5). See which
power sources it works with. Take
some notes in the project 38
table - it has a column for the
LED. You can replace the yellow
LED with the red LED (D1) and
compare it too if you like.
Project #41
Powering LED
Now replace the single LED with
the mini circuit shown here. See
which power sources light both
LEDs. Take some notes in the
project 38 table - it has a column
for Big Voltage.
This circuit needs the same
current as for the yellow LED by
itself. However, it needs higher
voltage to turn on both LEDs, one
after the other.
Project #42
Powering
Big Voltage
Now change to this mini circuit instead. Find out
which power sources can run both LEDs and
the horn. Take some notes in the project 38
table - it has a column for Big Current.
This circuit needs about the same voltage as
for the yellow LED by itself, but it needs higher
current to turn on both LEDs and the horn all at
the same time.
Project #43
Powering
Big Current