Theoretical background
The operation of a transformer is to reduce or increase the output voltage
with respect to the input voltage, it works by Faraday's law which says that a
changing magnetic field creates an electromotive force in the secondary
winding of the transformer.
Fig.1 Shows the operation of a transformer.
A transformer is made up of a core which is made up of two main parts: the
columns, which is the part where the windings are mounted, and the cylinder
heads, which is the part where the union between the columns is made. The
core is used to conduct the magnetic flux.
The winding is a copper wire wound through the core at one end and
covered by an insulating layer. It is made up of two coils, the primary and the
secondary. The ratio of turns of the copper wire between the primary and
secondary windings will indicate the transformation ratio.
Fig.2 Transformation ratio.
Some characteristics of transformers:
 The input and output power frequency is the same.
 All are governed by the laws of electromagnetic induction.
 The primary and secondary windings do not have an electrical
connection (except for the automatic transformers). The energy
transfer is carried out by the magnetic flux.
 Moving parts are not required to transfer power, so there is no friction
or winding losses as in other electrical devices.
Fig.3 Transformer with center tap.
These transformers with a center tap simply divide the output signal in half,
this will depend on the ratio of the transformer.
The voltage signal of a common plug is 127 Vrms and it oscillates as follows:
Fig 4. Voltage signal of a common socket.
The RMS voltage, or the root mean square (also called the effective voltage),
is a method of denoting a sinusoidal voltage waveform (AC waveform) as an
equivalent voltage that represents the DC voltage value that will produce the
same heating effect or power dissipation in the circuit as this AC voltage.
The peak voltage is obtained from the following formula:
𝑉𝑃 = 𝑉𝑅𝑀𝑆 ∗ √2
Materials
• Cable with plug and socket
• 127 volt rms plug
• Oscilloscope: is a measuring instrument for electronics. Represents a graph
of amplitude on the vertical axis and time on the horizontal axis presents the
values of the electrical signals in the form of coordinates on a screen, in
which normally the X (horizontal) axis represents times and the Y (vertical)
axis represents tensions.
Fig 5. Oscilloscope example.
In it we can see:
Display (screen): This shows us the waveforms and the measurements made.
Analog channels: These are the inputs for the analog signals, normally this is
where the oscilloscope tip is connected to connect to the circuit. There are
oscilloscopes with 2, 4, 6 or 8 analog channels.
Menu Buttons: Here is the navigation for all the oscilloscope options, such as
save, print, utilities, time and date, and so on.
Horizontal scale (time base): It regulates the position and time scale of the
signal, that is, we determine how many seconds, milliseconds, microseconds
per division we are going to visualize on the display.
Vertical Scale (Volts per division): It is used to regulate the amplitude of the
signal on the display, to appreciate better details or different signals.
Trigger: The trigger allows us to synchronize the sampling and capture of the
signal at a specific point. In a few words, it allows us to decide which part of
the captured waveform to see on the display.
Acquisition control buttons: They allow you to configure the capture speed,
the record length used, the sampling speed, among other parameters.
• Oscilloscope tip: it is the one that is connected to the oscilloscope to one of
the channel inputs, to measure the required circuit.
Bibliografia:
Aprender sobre la electronica. ¿Qué es el voltaje RMS?, de Aprender sobre la electronica Sitio
web: http://www.learningaboutelectronics.com/Articulos/Voltaje-RMS.php
TECSA. ¿Qué es un transformador eléctrico y cómo funciona?, de TECSA Sitio web:
https://www.tecsaqro.com.mx/blog/que-es-un-transformador-electrico/
AcMax. (lunes, 17 de agosto de 2020). Ociloscopio, de AcMax Sitio web:
https://acmax.mx/osciloscopio-partes
Conclusión individual:
A transformer is used to reduce the output voltage signal with
respect to an input voltage signal, it works only with alternating
current, so alternating current will come out in the same way, the
transformation ratio of said transformer will depend on the
manufacturer's specifications, Although these may have errors due
to manufacturing errors, it is possible to see variations in the
transformation values by using an oscilloscope to visualize the
signal.