9
Subject to change without notice
Examples:
Set deflection coefficient
D
= 50mV/div (0.05V/div),
observed display height
H
= 4.6div,
required voltage
U
= 0.05x4.6 = 0.23Vpp.
Input voltage
U
= 5Vpp,
set deflection coefficient
D
= 1V/div,
required display height
H
= 5:1 = 5div.
Signal voltage
U
= 230Vrmsx2
√
2 = 651Vpp
(voltage > 400Vpp, with probe 100:1:
U
= 65.1Vpp),
desired display height
H
= min. 3.2div, max. 8div,
max. deflection coefficient
D
= 6.51:3.2 = 2.03V/div,
min. deflection coefficient
D
= 6.51:8 = 0.81V/div,
adjusted deflection coefficient
D
= 1V/div.
The previous examples are related to the crt graticule reading.
The results can also be determined with the aid of the
∆
V cursor
measurement (
please note “Controls and Readout”
).
The input voltage must not exceed 250V, independent from the
polarity.
If an AC voltage which is superimposed on a DC voltage is
applied, the maximum peak value of both voltages must not
or –250V. So for AC voltages with a mean value of zero
volt the maximum peak to peak value is 500V
pp
.
If attenuator probes with higher limits are used, the probes
limits are valid only if the oscilloscope is set to DC input
coupling.
If DC voltages are applied under AC input coupling conditions
the oscilloscope maximum input voltage value remains 250V.
The attenuator consists of a resistor in the probe and the 1M
Ω
input resistor of the oscilloscope, which are disabled by the AC
input coupling capacity when AC coupling is selected. This also
applies to DC voltages with superimposed AC voltages.
It also must be noted that due to the capacitive resistance of the
AC input coupling capacitor, the attenuation ratio depends on
the signal frequency. For sine wave signals with frequencies
higher than 40Hz this influence is negligible.
With the above listed exceptions
HAMEG
10:1 probes can be
used for DC measurements up to 600V or AC voltages (with a
mean value of zero volt) of 1200Vpp. The 100:1 probe
HZ53
allows for 1200V DC or 2400V
pp
for AC.
It should be noted that its AC peak value is derated at higher
frequencies. If a normal x10 probe is used to measure high
voltages there is the risk that the compensation trimmer bridging
the attenuator series resistor will break down causing damage
to the input of the oscilloscope.
However, if for example only the residual ripple of a high voltage
is to be displayed on the oscilloscope, a normal x10 probe is
sufficient. In this case, an appropriate high voltage capacitor
(approx. 22-68nF) must be connected in series with the input tip
of the probe.
With
Y-POS.
control (input coupling to
GD
) it is possible to use a
horizontal graticule line as reference line for ground potential
before the measurement.
It can lie below or above the horizontal
central line according to whether positive and/or negative
deviations from the ground potential are to be measured.
Total value of input voltage
The dotted line shows a voltage alternating at zero volt level. If
superimposed on a DC voltage, the addition of the positive peak
and the DC voltage results in the max. voltage (DC + ACpeak).
Time Measurements
As a rule, most signals to be displayed are periodically repeating
processes, also called periods. The number of periods per second
is the repetition frequency. Depending on the time base setting
(
TIME/DIV.
-knob) indicated by the readout, one or several signal
periods or only a part of a period can be displayed. The time
coefficients are stated in
ms/div
,
µs/div
or
ns/div
. The following
examples are related to the crt graticule reading. The results can
also be determined with the aid of the
∆
T and 1/
∆
T (frequency)
cursor measurement (
please note “ Controls and Readout”
).
The duration of a signal period or a part of it is determined by
multiplying the relevant time (horizontal distance in div) by the
(calibrated) time coefficient displayed in the readout .
Uncalibrated, the time base speed can be reduced until a
maximum factor of 2.5 is reached. Therefore any intermediate
value is possible within the 1-2-5 sequence.
With the designations
L
= displayed wave length in div of one period,
T
= time in seconds for one period,
F
= recurrence frequency in Hz of the signal,
Tc
= time coefficient in ms, µs or ns/div and the relation
F
= 1/T, the following equations can be stated:
However, these four values are not freely selectable. They have
to be within the following limits:
L
between 0.2 and 10div, if possible 4 to 10div,
T
between 2ns and 5s,
F
between 0.5Hz and 300MHz,
Tc
between 20ns/div and 500ms/div in 1-2-5 sequence
(with X-MAG. (x10) inactive), and
Tc
between 2ns/div and 50ms/div in 1-2-5 sequence
(with X-MAG. (x10) active).
Examples:
Displayed wavelength L = 7div,
set time coefficient Tc = 100ns/div,
to be continued see next page
Basics of signal voltage
