Transcript Circuits for Grade 9 - technologerry.co.za

ELECTRONIC CIRCUITS
FOR GRADE 9
Prepared by G. C. Accom
SOME OF THE SYMBOLS WE WILL USE
SYMBOL
NAME
SYMBOL
NAME
SWITCH
LDR
BULB
RESISTOR
TRANSISTOR
CAPACITOR
BUZZER
DIODE
CELLS IN
PARALLEL
CELLS IN
SERIES
How to make a simple cell-holder for
batteries
USE A
PIECE OF
RUBBER
HOSE AND
A KNIFE
CUT A SLIT INTO THE HOSE
SLIDE THE NUMBER OF CELLS YOU
NEED INTO THE SLIT YOU HAVE CUT
I GRADE 9 YOU WILL BE WORKING WITH
THE FOLLOWING POWER SOURCES
EXPLAIN TO
LEARNERS
WHY WE SAY
THESE CELLS
ARE
CONNECTED
IN SERIES
A SIMPLE CIRCUIT WITH CELLS
CONNECTED IN SERIES
SWITCH MADE WITH PAPER CLIP AND THUMB TACK
PUSH SWITCH
ALWAYS ON
TOGGLE
SWITCH
PUSH SWITCH
ALWAYS OFF
PUSH SWITCH Normally ON in its
normal state
It switches OFF when you press it
PUSH SWITCH Normally OFF in its
normal state
It switches ON when you press it
CIRCUIT DIAGRAM FOR TWO CELLS
CONNECTED IN SERIES
SWITCH OPEN
SWITCH CLOSED
CELLS CONNECTED IN PARALLEL
Switch Open
CELLS CONNECTED IN PARALLEL
Switch Closed
BULBS CONNECTED IN SERIES
SEE WHAT HAPPENS WHEN ONE BULB
IS REMOVED
BULBS CONNECTED IN PARALLEL
SEE WHAT HAPPENS WHEN ONE BULB
IS REMOVED
AND SWITCH – Both Open
AND SWITCH – One Closed
AND SWITCH – Both Closed
OR SWITCH – Both Open
OR SWITCH – Bottom switch closed
OR SWITCH – Top switch closed
OR SWITCH – Both switches closed
4,5 v battery, switch, resistor and LED
CIRCUIT DIAGRAM
LDR, buzzer, 3v battery
Buzzer sounds when light of torch is
brought close
CIRCUIT DIAGRAM
LDR with LED
LED is ON in absence of LIGHT
LED is OFF in presence of LIGHT
CIRCUIT DIAGRAM
Circuit with switch, resistor,
capacitor, diode & LED
NOTE- LED is OFF
NOTE- LED is ON
NOTE POWER SUPPLY IS REMOVED
BUT - LED is still ON
CIRCUIT DIAGRAM
TOUCH OR MOIST DETECTOR
SWITCH OPEN = LED OFF
WATER
SWITCH CLOSED = LED ON
WATER
CIRCUIT DIAGRAM
YOU CAN USE EXACTLY THE SAME
CIRCUIT TO ADD A BUZZER
CONNECT TERMINALS OF BUZZER HERE
WATER