Thames & Kosmos Electronics - Flasher circuit

Flashers
EXPERIMENT 

Flasher circuit
YOU WILL NEED
  resistors,  Ω
  resistor,  kΩ
  resistor,  kΩ
  capacitor  µF
  capacitor  µF
  LEDs
  transistor modules
  short wire bridges
  long wire bridges
 electronics board
 battery clip
 and additional household
item: 9-volt square battery
HERE’S HOW
1. Assemble your circuit.
2. Connect the battery and watch
what happens.
As soon as you hook up the
battery, the green and red LEDs
start to light up in turn —
switching quickly every one or
two seconds.
 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
22 kΩ
LED 2
LED1
LED2
T1
+
–
T2
A
A
C
C
R2
 kΩ
C1  µF
R3  Ω
C2  µF
R
 kΩ
R
 Ω
+
+