How-to-guides - Understanding diodes
What is a diode and what
can it do for me?
semiconductor can get you out of a lot of trouble when you
need it. This one way traffic controller for electronics can
be used to isolate door triggers to changing an ac voltage
ready to learn more?
electronic components which have the ability to allow
current to flow in only one direction.
There are many
electrical systems circuits
which use diodes to prevent a back feed between circuits to
isolate the circuits and to prevent some current spikes.
Diodes are ideal for isolating an alarm, keyless entry, or
remote start from the factory wiring in vehicle.
Diodes are small
cylindrical shaped components which are consisted of two
leads, the Anode
and the Cathode.
The Cathode is the
striped side of
Usually a diode is
black in color with a gray
stripe, marking the Cathode side of the diode.
through a diode in one direction only.
When the Anode side
of the diode is facing towards the positive source of
voltage, it will allow the circuit to be completed, and is
considered Forward Biased.
If the Cathode side of the diode
is facing towards the positive source of voltage (Anode
towards negative source), then the diode will not allow the
circuit to be completed.
diagrams give an example of a circuit.
Flow and Electron Flow.
According to Conventional Current
Flow, current flows from positive to negative in the
direction that the voltage drops across the resistance,
or the “load”, in the circuit.
According to Electron
Flow, current flows from negative to positive in the
direction that the electrons flow.
Current Flow theory seems to be the most popular and is used
more often, therefore, the diagrams in the following
examples will be based on the Conventional Current Flow
Diode vehicle security system applications
diagram illustrates how a diode can be added to a
circuit to isolate the alarm or other device so that, when
activated, it will power just one of the components in a
circuit instead of all the components in the circuit.
example, in the circuit illustrated to the left, the factory
switch controls both bulbs because the current is flowing
through the circuit when the switch is used to power the
The same diode in Figure #2 could be considered Reverse
Biased, when the switch is
off and the alarm is activated, because it is allowing the
alarm to power
only one bulb and is blocking the current
from back feeding to the other components in the circuit.
Diodes Part 2