Elenco Circuit Maker Sound Plus 200 - Manual (Page 37)

-36-
Project #68
Press the press switch (S2) on and set
the adjustable resistor (RV) so the lamp
(L4) just lights. Slowly cover the
photoresistor (RP) and the lamp
brightens. If you place more light at the
photoresistor the light dims.
This is an automatic street lamp that
you can turn on by a certain darkness
and turn off by a certain brightness.
This type of circuit is installed on many
outside lights and forces them to turn
off and save electricity. They also come
on when needed for safety.
Automatic
Street Lamp
Project #69
Voice Control
Install the parts. The lamp (L4) will
be on. It will be off as long as you
blow on the microphone (X1).
Speaking loud into the mic will
change the brightness of the lamp.
Modify the circuit in the preceding
project by replacing the lamp (L4)
with the speaker (SP2). Blow into
the microphone and hear it in the
speaker.
Talk directly into the microphone.
You can hear your voice on the
speaker, though it may be badly
distorted.
Turn the slide switch (S1) on and there should be no sound.
The transistor is on so the voltage on U3 is low. Blowing on
the microphone (X1) turns transistor (Q2) off, the voltage on
U3 voltage goes high and the speaker will sounds.
Project #70 Blowing Off the Electric Light
The microphone is a resistor
that changes in value due to
the changes in air pressure on
its surface.
Project #71
Listen to
Your Breath
CM-200_Manual_031914.qxp_CM-200_Manual_031914 4/2/14 12:04 PM Page 37