Thames & Kosmos Electronics - Brief blinking

Flashers
EXPERIMENT 

Brief blinking
YOU WILL NEED
 your flasher circuit from
Experiment 12
  resistor,  kΩ
HERE’S HOW
1. Remove the 22-kΩ resistor (R1) and
replace it with the 100-kΩ resistor.
Do you notice something?
2. Wait a brief moment.
At first, when you exchange the
resistor, nothing happens at all
except for the green LED lighting
up.
But then the red LED flashes
quickly, while the green one briefly
goes out!
So, by switching the resistors, you
changed the circuit so that the red
LED blinks just briefly.
 WHAT’S HAPPENING?
+
–
9V
T2
T1
R 2
220 kΩ
+
10 µF
C 2
+
100 µF
C 1
LED 1
R 4
470 Ω
R 3
470 Ω
R 1
100 kΩ
LED 2
LED1
LED2
T1
+
–
T2
A
A
C
C
C1  µF
R3  Ω
R
 Ω
R2
 kΩ
C2  µF
R
 kΩ
+
+