Elenco Circuit Maker Sound Plus 200 - Manual (Page 21)

Project #25
Parallel Lamps
-20-
Turn on the slide switch (S1) and the speaker sounds as the lamp (L4)
lights. The speaker and lamp are in series. The transistor is used to
increase the voltage on the lamp, otherwise it wouldn’t light
Turn on the slide switch
(S1) and the LED (D1) and
lamp (L4) light. If one of the
them is broken then the
other will still be on,
because they are in
parallel. An example of this
is most of the lights in your
house; if a bulb is broken on
one lamp then the other
lamps are not affected.
When there is light on
the photoresistor (RP),
its resistance is low and
the LED (D1) will flicker.
Shield the photoresistor
from the light; the LED
should turn off.
Project #27
Two-Transistor Light Alarm
Build the circuit with the
jumper connected as shown,
and turn it on. Nothing
happens. Break the jumper
connection and the lamp (L4)
turns on. You could replace
the jumper with a longer wire
and run it across a doorway to
signal an alarm when
someone enters.
Project #24
Sound & Light in Series
Project #26
Light-Controlled LED
CM-200_Manual_031914.qxp_CM-200_Manual_031914 4/2/14 12:04 PM Page 21