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Setting up the light show...................................................................

The circuit won’t mean a thing if you don’t set up the lights for it to control.

That’s where the elements of the LED/resistor arrays come in. An array, in

this case, equals the lights that define one whole dolphin.

These five arrays each include

38 LEDs, which light up when a river of current runs through them

19 resistors,which are resistors that limit the current running through

the LEDs in series with each resistor to approximately 10 milliamps

Take a look at the schematic for these in Figure 10-4. Notice that we have not

assigned a number to each LED and resistor. That is because we have 190

LEDs and 95 resistors among the 5 dolphins — and we don’t have time.

These LEDs and resistors are wired together such that two LEDs and one

resistor are in series. When +V is applied, current runs through each compo-

nent sequentially. Each group of two LEDs and one resistor are connected

parallel with the other groups of LEDs and resistor. Because 19 LED/resistor

groups are in each array, the total current running through an array is

approximately 190 milliamps.

Square Wave

Pin 3

Pin 2

Pin 4

Pin 7

Pin 10

Figure 10-3:
You put in
one square
wave to get
out multiple
sequential
little pulses.

Chapter 10: Dancing Dolphins 219