Elenco 130-in-1 Electronics Playground - Manual (Page 49)

-49-
V. MORE FUN WITH DIGITAL CIRCUITS
Do you sleep late? Even if you do, don’t fear!
Because you can make the siren in this circuit alarm
so that wakes you up gradually as the day dawns.
Set the switch to position B, construct the circuit, then
set the switch to position A to turn it on. You should
hear sound from the speaker.
When you expose the CdS cell to light, the siren
sounds. The siren sound stops when you cover the
CdS. The alarm siren is made with a multivibrator,
and controls its operation with the CdS.
When you go to bed at night and sleep with your
room dark, turn on this circuit. The next morning, the
alarm siren will wake you up.
Notes:
EXPERIMENT #93: GET UP SIREN
-112-
Schematic
Wiring Sequence:
o 1-29
o 2-30
o 3-116
o 5-83-108-70-121
o 15-63-132
o 16-81
o 67-90-92-115
o 91-68-107
o 69-82-84-89
o 119-124
o 122-131