Tektronix TYPE L Instruction Manual page 12

5. The final number is the voltage difference
between the maximum
of the input signal. DEFLECTION x VOLTS/CM
x ATTENUATION = VOLTAGE. For example,
in Figure 2-3, the vertical deflection between
" a" and " b" is 4.0 cm. If the AC-DC switch
is at AC, the VOLTS/CM switch at .5 (black
numbers), and the signal is applied through
a 10X probe, the voltage calculation would be:
(4.0 cm) x (0.5 VOLTS/CM) x (10) = 20.0 volts.
M easuring Peak-to-Reference
Voltages
It is often desired to measure the voltage
of a waveform with respect to some reference
voltage, usually ground.
as follows:
1. Set the AC-DC switch at DC position.
2. Connect the appropriate interconnecting cable
o r probe to the INPUT connector, using the
necessary attenuators and terminations.
3. Adjust the controls of the oscilloscope and
plug-in for a free-running trace. Be sure the
V AR IAB LE (VOLTS/CM) control is in the C A L I­
BRATED position.
4. Touch the input cable to the oscilloscope
ground terminal or to the reference voltage
being used. Adjust the V ERTIC AL POSITION
control to set the trace at some convenient
reference position such as (b) in Figure 2-4.
5. Without changing the position of any controls
of the instrument, remove the cable from the
reference voltage (ground) and connect it to
the voltage signal source
2-6
and minimum peaks
This may be done
to be measured.
Operating Instructions - Type L Plug-In
Adjust the oscilloscope triggering controls for
a stable display. If the amplitude of the signal
is inconveniently large or small, reset the
VOLTS/CM switch fo r a more suitable value
and repeat the above procedure.
6. Determine the vertical distance on the o s c il­
loscope graticule between the waveform peak
and the original trace position. Recheck the
reference level.
Fig. 2-4. Measurement of peak-to-reference signal level.
7. Calculate the dc voltage level in the same
manner as peak-to-peak voltage is calculated:
DEFLECTION x VOLTS/CM x ATTENUATIO N=
VOLTAGE. F or example, in Figure 2-4 the
vertical distance between
4 cm. If the reference voltage is ground,
the VOLTS/CM switch is set at .2 and the
total attenuation ratio of the connecting system
is 15:1, the voltage
(4cm) x (0.2 VOLTS/CM) x (15) =
above ground, or + 12 volts.
" a" and " b" is
calculation would be:
12 volts
AA