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 = 0.23V
pp
.
Input voltage
U
= 5V
pp
,
set deflection coefficient
D
= 1V/div,
required display height
H
= 5:1 = 5div.
Signal voltage
U
= 230Vrmsx 2
?√
2 = 651V
pp
(voltage > 160V
pp
, with probe 10:1:
U
= 65.1V
pp
),
desired display height
H
= min. 3.2div, max. 8div,
max. deflection coefficient
D
= 65.1:3.2 = 20.3V/div,
min. deflection coefficient
D
= 65.1:8 = 8.1V/div,
adjusted deflection coefficient
D
= 10V/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 400V, 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 -400V. So for AC voltages with a mean value of
zero volt the maximum peak to peak value is 800V
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 400V.
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 1200V
pp
. 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 repea-
ting 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 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 5ns and 5s,
F
between 0.5Hz and 100MHz,
Tc
between 50ns/div and 500ms/div in 1-2-5 sequence
(with X-MAG. (x10) inactive), and
Tc
between 5ns/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,
required period T = 7x100x10
-9
= 0.7µs
required rec. freq. F = 1:(0.7x10
-6
) = 1.428MHz.
Signal period T = 1s,
set time coefficient Tc = 0.2s/div,
required wavelength L = 1:0.2 = 5div.
Displayed ripple wavelength L = 1div,
set time coefficient Tc = 10ms/div,
required ripple freq. F = 1:(1x10x10
-3
) = 100Hz.
TV-line frequency F = 15625Hz,
Type of signal voltage
