Data Sheet
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49. History of LEDs
Build the circuit as shown on the left and you will light up the
star LED (70). If you want to turn on the heart LED (69) and
the bi-directional LED (71), you must press the press switch
(61) or touch the reed switch (83) with the magnet (7).
The lighting industries as a whole are pushing LEDs to replace
incandescent sources in a variety of applications, but the rst
time that LEDs actually did displace incandescent lamps was
in vehicle brake lights, signal lights, and trafc lights back in
1987.
50. Master Switch
Build the circuit as shown on the left. Turn on the switch (61),
then press the press switch (61) and you will light up the lamp
(76) and the bi-directional LED (71) at the same time.
This type of circuit simulates a house with a master switch
that you need to turn on rst (the switch (62)) before you can
turn on any light in the house with the press switch (61).
2nd level