Tesla BM 510, Instruction Manual

Page: 19 / 54

Ziskâni referenćni ûrovnë
Referenćni ûroven ziskâme nâsledujiclm po-
stupem:
Pripojime hrot sondy na zemni s vor ku na pri-
stroji [nebo na pfislusnÿ zdroj napëti, je-li
üroven jinâ nez zem) a nastavime oscilograf
na volnë bëzici zâkladnu. Je-li jako referenćni
üroven zvolen zemni potenciâl, lze też pouźity
vstup pfepnout pfepinacem S201 do polohy „0“.
Vertikélnë nastavte stopu na stinitko tak, aby
lezela na nëkteréni z hlavnich dilkû rastru
(tento bod nastaveni bude zâviset na polarité
a amplitude vstupniho signélu, event, na po-
uzitém vstupu zesilovace). Tento dilek rastru
je pak referenćni ûrovni pro vsechna dalsi
mëreni. Po nastaveni referenëni ûrovnë uż ne-
nastavujeme vertikâlni posuv, nebot: by do më-
feni była zanesena chyba.
Hrot sondy pripojime na zdroj mëficiho napëti.
Ovlâdaci prvek „Citlivost“ (R119) nastavime
tak, aby obraz byl stabilni.
Na rastru odmërime vzdâlenost pozorovaného
bodu na prûbëhu od bodu, kterÿm probihâ re­
ferenćni ûroven v dilci. Tento rozmër nâso-
bime iidajem, kterÿ je dân polohou knofliku
„V/dil“.
Nśsobime jeStS dćlicim pomorem poużitś sondy.
Pro nazornost predpokladejme pouźiti sondy
BP 4631 s dglicim pomgrem 1 :10. Knoflik V/dil
v poloze 0,2; referenćni uroveii je nastavena
na druhou rysku od spodku rastru a od tohoto
bodu je vzdalenost 3 dilky k bodu prubćhu, ve
kterem chceme mgfit okamżitg napgti. Potom
bude: 10 x 0,2 x 3 = 6 V. Je-li mereny napefovy
bod nad rovinou referenćni urovne pri pouziti
vstupu „ Y l“, je polarita napćti kladna; je-li
pod urovni, je zśpornś. Pri pouźiti vstupu „Y2“
je polarita napśti opaćna.
Mereni Casu
Casova zśkladna poużitd v pfistroji umozńuje
zjistit casovy interval mezi dvema prubghy
nebo dvgma body jednoho prubShu aż do dślky
rastru. Takove mćreni se provddi nasledujicim
zpusobem:
Na rastru odecteme horizontalni vzdalenost
mezi dvgma body, jejichż casovy interval ode­
cteme v dilcich.
Tuto vzddlenost nasobime koeficientem, ode-
Ctenym v poloze knofliku „ćas/dil“ pouźite ca-
sove zakladny. Potenciometr jemne regulace
zesileni horizontślniho zesilovaCe nastavime
do polohy „Kai.
ĆZ“.
Pro nśzornost predpokladejme, źe prepinac
„cas/dil“ je v poloze 1 msec; horizontalni vzd&-
lenost, odectena na rastru, je 5 dilku. Casovy
interval potom bude:
5 x 1 msec = 5 msec.
Provision of Reference Level
The reference level is provided as follows:
Insert the probe point into the earth terminal
of the instrument [or connect it to the desired
voltage supply, if the level is other than earth)
and set the oscilloscope to allow the time base
sweep freely. If the earth potential is chosen
as reference level, the input used can also be
switched to “0 “ by means of the switch S201.
Adjust the vertical setting to make the elec­
tron trace coincide with one of the main g ra­
ticule divisions (the preset point will depend
on thet polarity and amplitude of the input
signal and on the amplifier input chosen).
This graticule division now serves as reference
level in all subsequent measurements. After
having preset the reference level, avoid any
adjustment of the vertical shift, since this
would infer error into the measurement.
Apply the point of the probe to the source of
the voltage being measured. Set the “TRIG.
SENSITIVITY“ potentiometer (R119) so as to
obtain a stable image.
Now measure the distance of the point being
observed on the curve from the reference le­
vel point in terms of graticule divisions. Mul­
tiply this distance by the value indicated by
the position of the “V/DIV.“ knob. Moreover,
multiply the product so obtained by the divi­
sion ratio of the probe used.
To illustrate the calculation, let us assume the
use of the BP
4631
probe with a division ratio
of
1
:
10,
the “V/DIV.“ knob being in the posi­
tion
0.2.
Let the reference level be adjusted
to the second graticule division from below,
the distance from this point to the point on
the curve at which we wish to measure the
instantaneous voltage being
3
divisions. It fol­
lows that:
1 0 x 0 . 2 x 3 = 6
V. If the
“Y l “
input
is used and the measured voltage point is over
the reference level, the polarity of the voltage
is positive, and it is negative, if the said point
is below the reference level. When using the
“Y2“ input, the polarities are reverse.
Time Measurements
The time base used in the instrument enables
to evaluate the time interval between two cur­
ves or between two points of the same curve,
the limit being imposed by the length of the
graticule. The measurement of this kind pro­
ceeds as follows:
Read off the horizontal distance between two
points on the graticule in terms of divisions.
Multiply this distance by the factor indicated
by the position of the “TIME/DIV.“ knob of
the time base. Set the fine gain-adjustment
potentiometer of the horizontal amplifier to
the position “T. B. CAL.“.
To illustrate the evaluation, let us assume the
“TIME/DIV.“ switch to be in the position
1 msec, the horizontal distance read off the
graticule being 5 divisions. The time interval
will then be: 5 x 1 msec = 5 msec.
17