Elenco Upgrade Kit SC500 to SC750 - Manual (Page 52)

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Project #614
OBJECTIVE: To construct a circuit that indicates if a door is
open or closed using light.
Open & Closed
Indicator
Switching from letters “O” to “C” requires turning off segments B & C.
Turn on the slide switch (S1), the display lights an “O” indicating an
open door. Cover the photoresistor (RP) with your hand (closed door)
and the letter “C” lights. The photoresistor turns Q2 on and off
depending on the amount of light. When Q2 is on (light on RP) the
voltage at the collector is low, lighting segments B & C. Covering the
RP turns Q2 off and the collector voltage is high now. Segments B &
C turn off and the letter “C” lights.
Project #615
OBJECTIVE: To construct a circuit that indicates if a switch is
open or closed using U4.
Open & Closed Indicator (II)
As in project #614, the display will light an “O” or “C” indicating if the press switch
(S2) is on or off. Turn on the slide switch (S1), the LED (D2) and letter “O” lights.
With no input to U4 the LED lights and the voltage decreases enough so segments
B & C light. Press the press switch S2, the LED turns off and the letter “C” lights.
The voltage at U4’s output increased enough turning the segments off.
OBJECTIVE: To construct a circuit that indicates vibration.
Vibration Indicator
Project #616
Modify project #615 by replacing the press switch (S2) with the whistle chip
(WC). As you tap the whistle chip, U4’s output voltage changes, lighting the
LED (D2) and changing the display from “C” to “O”.
To learn more about how circuits work, visit www.snapcircuits.net or page 85 to find out about our Student Guides.