5-2
CONVERTING ALTERNATING CURRENT
TO DIRECT CURRENT
In order to charge a battery, it is necessary to convert
alternating current (A.C.) to direct current (D.C.). This is
accomplished by using a diode or rectifier. (Illust. 5-2) A
single diode makes use of only one half of the A.C. signal.
This is known as HALF WAVE RECTIFICATION. (Illust.
5-3) In certain situations it is necessary to make use of
the entire A.C. signal. To accomplish this, multiple diodes
in a bridge configuration are used to produce FULL WAVE
RECTIFICATION.
CONDITION: All wiring must be fully insulated, securely
fastened and free of foreign materials (such as rust and
corrosion) at the connection points. This is especially
important with the use of batteries, as much of the
potential may be lost due to loose connections or
corrosion. Remember to check the insulation on the wire.
All it takes is a pinhole for leakage to “ground out” on the
engine or frame. This is of special concern when moisture
or water is present.
WIRE GAUGE: The proper thickness of wire is
necessary in all electrical circuits. Wire diameter is
measured in increments of gauge numbers. As the gauge
number of the wire increases, the wire diameter
decreases in size. (Illust. 5-4)
5-4
5-2
5-3
Current flows through a diode when the anode is more
positive than the cathode. The cathode end of the diode
should point toward the battery when a diode is used
between a charging system and a battery.
Half Wave Rectifier Single Diode
The single diode allows only the positive half of the A.C.
signal through. It does not allow the negative portion
through.
Full Wave Rectifier Bridge Rectifier
The full wave rectifier makes use of the entire A.C. signal,
converting it to D.C.
COMPONENTS
BATTERY
The batteries used in conjunction with Tecumseh engines
are 12 volt lead acid or “maintenance free” style. The
chemical energy produced by the dissimilar metals of
the battery plates provides an electrical potential that is
used to power the electric starter or unit accessories.
Consult the original equipment manufacturer’s service
manual for battery size, capacities, and testing
procedure.
WIRING
The wires used in Tecumseh electrical systems are
copper stranded with an insulated coating around the
copper strands.
ANODE
CATHODE
BAND OR OTHER
MARKING INDICATES
CATHODE END
HALF WAVE RECTIFIER
(SINGLE DIODE)
+ VOLTAGE
- VOLTAGE
+ VOLTAGE
- VOLTAGE
A.C. INPUT
D.C. INPUT
THE LARGER THE NUMBER THE SMALLER THE WIRE
# 18
# 6
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