Diodes are extremely useful semiconductor devices. They have the interesting characteristic that they will pass a current in one direction, but block it from the other. They can be used to allow currents to flow from one part of a circuit to another but prevent other currents from “backwashing” where you don’t want them.
The schematic symbol for a diode is shown in Figure 2-29. The arrow indicates the direction of
conduction. The arrow represents the
or positive side, of the diode, while the bar represents the
or negative side, of the diode. A higher voltage on the left of the
component will allow current to be passed through to the right.
However, a higher voltage on the right will prevent current flow to
Figure 2-29. Schematic symbol for a diode
Diodes have a
when conducting. This means that there
will be a voltage difference between the anode and the cathode. For
example, a diode may have a forward voltage drop of 0.7V. If this
diode is part of a larger circuit and the voltage at the anode is 5V,
then the voltage at the cathode will be 4.3V.
Diodes are useful for removing negative voltages from a signal, a
process known as
may be combined together to form a bridge rectifier, as shown in
Figure 2-30. The bridge “flips” the negative components of the wave so that only a positive voltage is present ...