Suzuki DF 2.5 Service Manual page 40

OPERATION
The transistorized ignition circuit will be discussed by referring to the diagram below:
When the recoil starter is pulled, the flywheel is turned. An electromotive force generated in the primary
winding (n ) of the ignition coil makes the transistor (TR
1
mary circuit (indicated by dashed lines).
As the flywheel turns further, the primary current increases, and the terminal voltage of the circuit consisting
of the resistor (R ) and transistor (TR
1
the series circuit (R and R
2
minal voltage of the resistor (R
transistor (TR ) when the ignition timing approaches, and thus the transistor (TR
2
the base current of (TR
from the conductive state.
The current flowing through the primary winding (n
magnetic flux across the ignition coil. The result is a high surge voltage in the secondary winding (n
TRANSISTOR
R
1
R
2
TR
R
3
) increases. This increases the working voltage at the connection of
1
) connected in parallel to the primary circuit. As the flywheel turns further, the ter-
3
) in the resistor circuit (R
3
) flowing through the resistor (R
1
TR
1
2
FLYWHEEL
MAGNETO
) conduct through the resistor (R
1
and R ) rises to the level of working voltage of the
2 3
) is by-passed, and the transistor (TR
1
) is thus interrupted, and a rapid change occurs in the
1
IGNITION
COIL
n n
1 2
S N
IGNITION AND ELECTRICAL 3-3
) and forms the pri-
1
) is turned on. As a result,
2
) is turned off
1
).
2
EMERGENCY/
SPARK
ENGINE STOP
PLUG
SWITCH