Elenco Green Projects - Manual (Page 63)

+
5V
Project #99
-62-
Sound Pulse
Speed Indicator
Set the slide switch (S5) to position B;
the fan spins and the red LED (D1)
lights. The voltage across the motor
(M4) is shown on the meter, it should be
about 1V. The yellow LED (D5) is in
parallel with the motor and does not light
with only 1V across it. Spin the motor
faster by blowing on the fan; the voltage
across increases and the yellow LED
lights.
Blow on the fan see what voltage it
takes to turn off the red LED and turn on
the yellow LED.
Pushing the press switch (S2) bypasses
the red LED, so the fan spins faster and
the yellow LED lights. See what the
voltage is across the motor now.
Set the switch (S5) to position B, you
hear a short tone from the horn (W1). As
the 470
μF capacitor (C5) charges,
current flows through the horn. Set the
switch to position C, and watch the
voltage on the meter (M6) as the
capacitor discharges. Move the switch
between B and C several times slowly.
Add the press switch (S2) across base
grid locations C5-C7, on level 4. When
the slide switch is in position B, pressing
S2 bypasses the capacitor and the horn
sounds. When the slide switch is in C,
pressing S2 discharges the capacitor
instantly.
Project #98
+
5V
See projects 1 & 3 if you need to
recharge the battery (B4).