Elenco LIGHT - Manual (Page 71)

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Project 155 Mini Battery Project 154
Modify the project 152
circuit to be this one,
which has the
adjustable resistor (RV)
instead of the 5.1k
Ω
resistor (R3). Use the
lever on RV to adjust the
capacitor charge &
discharge rate, setting it
towards the red LED
(D1) will make the LEDs
flash brighter but get
dim faster.
Charging & Discharging Project 153
Mini
Capacitor
Use the project 152 circuit but
replace the 100
µ
F capacitor
(C4) with the 0.1 µ F capacitor
(C2). The circuit works the same,
but the LEDs will only light very
briefly, because the smaller
0.1
µ F capacitor stores much
less electricity than the larger
100
µ F capacitor.
Project 152
Turn on the slide switch (S1) for a few seconds, then
turn it off. The red LED (D1) is dimly lit for a few
moments but goes completely dark as the batteries
(B1) charge up the 100
µ F capacitor (C4). The
capacitor is storing electrical charge.
Now press the press switch (S2) for a few seconds.
The white LED (D6) is initially bright but goes dim as
the capacitor discharges itself through it.
The C4 capacitor value (100 µ F) sets how much
charge can be stored in it, and the R3 resistor value
(5.1k
Ω
) sets how quickly that charge can be stored or
released.
Now swap the locations of the white & red LEDs, and
try the circuit again. Both LEDs have the same
electrical current flowing through them, but white LED
is much brighter than the red LED because it is a
super-bright LED while the red one isn’t.
Adjustable
Charging &
Discharging
This circuit is similar to the
preceding one, but may be
easier to understand. Set the
lever on the adjustable resistor
(RV) towards the 100
µ F
capacitor (C4). Place the white
LED (D6) across the points
marked B & C; the LED lights
as the capacitor charges.
Next, place the white LED
across points A & B instead;
now the LED lights as the
capacitor discharges. Move
the white LED back to B & C
and repeat. Use the lever on
RV
to vary the charge /
discharge rate.
The capacitor is storing
energy like a mini battery.