Transistors
The history of the transistor—also known as the “transistor—began
back in the days when tubes were used in computers. The focus of research at
the time was precisely the improvement and reduction in the size of the valves,
in addition to increasing their
efficiency, as they consumed a lot of energy.
Therefore, it was necessary for the valves to be replaced with a
new, smaller and cheaper component. Military research began to become more and
more complex and demanded that computers be reduced in size and could work at
higher frequencies. The valves were not capable of this, leading electricians
to look for other components.
In November 1947, scientists at the Bell Telephone laboratory
discovered the transistor, although their research tried to go in another
direction. They found that when a certain voltage was applied to one of the
component's terminals, the signal that was output at the other terminal was
amplified. Thus, the transistor became responsible for signal amplification, in
addition to serving as a controller that interrupts or releases the passage of
electrical current.
Its low cost allowed it to become an almost universal component for
non-mechanical tasks. Transistors today have replaced almost all
electromechanical devices in most control systems, and appear in large
quantities in everything from electronics to cars.
Darlington Transistor Operation
Every transistor has three terminals, Collector, Base and Emitter.
One of the terminals receives the electrical voltage (Base), and the others
send the amplified signal (Collector to Emitter). The Base terminal is
responsible for controlling this process, since the electrical current that
enters and leaves the Collector and Emitter only when electrical voltage is
applied to the Base terminal.
For simplicity, we can think of the transistor as a faucet.
The side of the pipe coming from the street is the inlet terminal
(Collector) and the side from which it exits to the water is the outlet
terminal (Emitter). When you turn the faucet on or off, your hand acts as the
terminal (Base). However, we must remember that in Darlington transistors there
are only two stages, it will either be on or off, comparing again with the tap,
or it will be fully open or fully closed.
How to Test a Darlington Transistor?
NOTE: Use the multimeter on the Semiconductor scale.
1st test: the red tip must be on the BASE as a reference and
when measuring it should not be removed, place the black tip on the COLLECTOR the measurement
should be 0.3V to 0.8V. Then place the black tip on the SENDER and the
measurement will be greater than 0.7V.
2nd test: put the black tip on COLLECTOR or on the carcass,
and the red tip on the BASE and the measurement will be from 0.3 to 0.8v.
Then put the red on theISSUER the measurement should also be from 0.3v to
0.8V. None of the terminals should be shorted.
Mosfet Transistor Operation
Physically it is the same as the Darlington transistor, but
internally it has changes. The Mosfet transistor controls the current flowing
between the “Source and Drain” terminals, through the voltage applied to the
Gate terminal. Application codes for Mosfet Transistors usually have the
initials IRF, 2SK and BUZ.
When voltage is applied to the Gate terminal, it allows electrical
current to flow through the other Source and Drain terminals. The amount of
voltage applied to the Gate (or control terminal) will determine how much
current will be output through the terminal. If no voltage is applied to the
control terminal, there is no electric current flowing.
Comparing again to a faucet, the more you open the register, the
more water tends to come out, as with the Mosfet transistor, the greater the voltage
applied to the Gate terminal, the greater the electric current that will flow
from the Source to the Drain.
How to Test a Mosfet Transistor?
With the multimeter on the semiconductor scale, place the red tip
into the SOURCE terminal and the other black tip into the SOURCE terminal. DRAIN the measurement will
be 0.3V at 0.8v. None of the terminals should be shorted.
REMINDER: To identify the component's function, it must
be verified through datasheet (data sheet), because physically we have several
equal components, the only difference (visual) is the numbering.