Scientech 801C
Scientech Technologies Pvt. Ltd.
14
Magnitude of Signal Voltage:
Generally alternating voltage data normally refers to effective values (rms = root mean
square value). But, for signal magnitude and voltage in Oscilloscope tests the volt peak-
to-peak (Vpp) value (which is the value of real potential difference between the most
positive and most negative points of a signal waveform) is taken.
To convert a value of sinusoidal wave displayed on the Oscilloscope screen to its
effective value, the resulting voltage peak-to-peak value has to be divided by 2.83.
Conversely V
pp
is 2.83 times V
eff
(Vrms) and is equivalent to the sinusoidal voltage.
The relations of the different voltages magnitude is given in the figure 1.
Figure 1
The minimum required voltage on the Y input for a display of 1cm amplitude is
2mVpp. However, smaller signals can be displayed. The deflection coefficients on the
input attenuators are indicated by Vpp/cm or mVpp/cm. The magnitude of the applied
voltage is ascertained by multiplying the selected deflection coefficient with the display
amplitude in cm. If an attenuator probe x10 is used, a further multiplication by 10 is
required with direct connection to the Y input, signals upto 160Vpp can be displayed. If
the applied signal is superimposed on a direct voltage, the total value (DC Peak value
of the alternating voltage) of the signal on the Y input must not exceed 400V.
Time Values of Signal Voltage:
As a rule all signals displayed are repeating process having a recurring frequency or
repetition rate which can be designated as "periods per second". For this, the units are
indicated on the "Time Base" switch
s/cm, ms/cm and s/cm. accordingly, the
"Time Base" dial is subdivided into two sectors. The duration of a signal period or a
portion of the waveform is obtained by multiplying the relevant time fine control
marked "Var" must be in its calibrated position for accurate measurement (arrow
horizontal and pointing to the left).
