Elenco Snap Circuits SOUND &reg - Manual (Page 76)

Project 164 Little Battery
Set the knob on the 500k W adjustable resistor (RV3) to the
left. Place the color LED (D8) across the points marked B &
C (“+” to B); the LED lights as the capacitor charges. Next,
place the color LED across points A & B (“+” to A) instead;
now the LED lights as the capacitor discharges. Move the
color LED back to B & C and repeat. Use the knob on RV3
to vary the charge / discharge rate, but keep it close to the
left (otherwise the LED would be too dim to see).
The capacitor is storing energy like a little battery.
Project 165
Tiny Battery
Use the preceding circuit, but
replace the 470
m F capacitor (C5)
with the smaller 1 m F capacitor
(C7). Set RV3 all the way to the
left. Place the color LED across B
& C to charge C7, then across A
& B to discharge it. The LED will
only flash for a moment, because
C7 can’t store much electricity
(C5 holds 470 times more). The
LED is easier to see in a dimly lit
room.
Set the knob on the 500k W adjustable
resistor (RV3) to mid-range. Place the
470
m F capacitor (C5) across the
points marked B & C (“+” to C), then
SWING its “+” side around to point A
(without unsnapping it from point B).
Swing its “+” side between points C &
A several times.
When the capacitor (C5) touches point
C, the color LED (D8) flashes to show
that the batteries charged up the
capacitor. When the capacitor touches
point A, you hear beep from the
speaker (SP2) to show that the audio
circuit discharged the capacitor.
You can change the “beep” sound a
little by turning the knob on RV3.
Batteries can hold a lot
more electricity than
capacitors because
batteries store chemical
energy while capacitors
store electrical energy.
Project 166 Little Battery Beep
The capacitor is storing
energy like a little battery.
The “beep” you hear is the
voice changer (U27) entering
recording mode, but you
can’t make any recording
with this circuit. Capacitor C5
can’t store enough electricity
to operate the voice changer
circuit, but it can power it long
enough to make a beep.
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