User Manual

Project 141
Dim Green Light
Project 140
No Blue Light
Turn on the slide switch (S1). The red, green, and yellow LEDs (D1, D2,
& D10) should be on, along with the red, green, and possibly the blue
LEDs on the disco motor (DM). The blue LED on the disco motor may
be dim or off.
YELLOW
Use the preceding circuit, but add the press
switch (S2) across the points marked A & B.
Turn on S1 and push S2. With S2 pressed, the
LEDs on the disco motor all shine brightly, but
the others are off.
Use the preceding circuit, but place the S2
across points A & C instead of across points A
& B. Turn on S1 and push S2. With S2
pressed, the LEDs on the disco motor are off,
but the others are shining brightly.
The battery voltage is split between two groups
of LEDs - the D1/D2/D10 LEDs, and the
red/green/blue LEDs in the disco motor. The blue
LED in the disco motor needs more voltage to
operate properly than the other colors, and the
reduced voltage to it may not be enough to light
it. The red & green LEDs in the disco motor may
be brighter than the D1 & D2 LEDs of the same
color, due to the quality an style of the actual
LEDs used.
Use the project 138 circuit, but remove 2 of the 3
LEDs (leaving D1, D2, or D10), in the 4 combinations
shown below. Compare the brightness of the different
LEDs in the disco motor (DM).
A. D1 in, D2 & D10 out.
B. D2 in, D1 & D10 out.
C. D10 in, D1 & D2 out.
D. D10 in but reversed (so it is red), D1 & D2 out.
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Project 138
Where’s the Blue Light?
Here the battery voltage is split between the
remaining LED (D1, D2, or D10) and the group of 3
LEDs in the disco motor. Green LEDs take a little
more voltage to operate properly than red or yellow
LEDs, so the green LED in the disco motor will be
dimmer than the red LED there (but not as dim as the
blue LED there). This effect is more apparent when
the green D2 LED is in the circuit (combination B).
Project 139
There’s the
Blue Light
Pressing S2 bypasses the D1,
D2, & D10 LEDs, so the LEDs
on the disco motor get the full
battery voltage, making them
brighter. This really helps the
blue LED on the disco motor,
because it needs lots of
voltage to operate properly.
Pressing S2 bypasses the
LEDs in the disco motor, so the
D1, D2, & D10 LEDs, get the
full battery voltage, making
them brighter.