were used in finding the vertical distance for
voltage measurements. The method for measur
ing a time interval is as follows:
1. Using the graticule, measure the horizontal
distance in centimeters between the points whose
time interval you wish to find.
2. Multiply the distance measured by the setting
of the TIME/CM control to obtain the apparent
time interval.
3. Divide the apparent time interval by the
magnification indicated by the setting of the
HORIZONTAL DISPLAY switch to obtain the cor
rect time interval.
Fig. 3-8. Measuring the time interval (period) of one
complete cycle of a periodically recurrent waveform.
The horizontal distance in centimeters of one complete
cycle (in this case 3 centimeters) is multiplied by the
setting of the TIME/CM control and is divided by the
sweep magnification to obtain the time interval. The
frequency of the waveform is the reciprocal of its time
interval.
FREQUENCY MEASUREMENT
The frequency of a periodically recurrent
waveform can be determined if the time interval
(period) of one complete cycle of the waveform
is known. This time interval can be measured by
means of the procedure described in the preced
ing paragraph. The frequency of a waveform is
the reciprocal of its time interval.
DC BALANCE ADJUSTMENT
If the trace moves vertically as the SENSI
TIVITY control is rotated, this indicates a need to
readjust the DC BAL control. This control is used
to compensate for any dc unbalance in the verti
cal amplifier. This unbalance will be particularly
noticeable on the high sensitivity ranges of the
SENSITIVITY control. To adjust the DC BAL con
trol, ground the oscilloscope input, place the
SENSITIVITY control at 20 VOLTS PER CM, and
rotate the TRIGGERING LEVEL control to the
RECURRENT position. Set the DC BAL control at
mid range and position the sweep so that it lies
under the proper base line. Rotate the SENSI
TIVITY control to the 200 /xVOLTS PER CM posi
tion, pausing at each range to adjust the DC
BAL control so that the trace remains on the base
line. (If the DC BAL control does not have suf
ficient range, it will be necessary to readjust the
appropriate COARSE DC BAL control located
inside the instrument. See the Calibration Pro
cedure, Section 6.) The trace should now remain
stationary as the SENSITIVITY control is turned
through its entire range of positions.
AUXILIA R Y FUNCTIONS
Calibrator
The calibrator is a source of accurately cali
brated square waves at a frequency of approxi
mately 1 kilocycle (±30%). The output ampli
tude is accurate within 3% of the SQUARE-
WAVE CALIBRATOR switch settings for no load
conditions. The primary function of the calibra
tor is to provide a convenient method for check
ing the calibration of the vertical-deflection sys
tem and for adjusting the probes. It can be used
for other purposes, however, if certain limitations
are kept in mind.
NOTE
AH output impedance figures given
for the calibrator are made with the
assumption that the output cathode
follower is conducting.
OPERATING INSTRUCTIONS — TYPE 502
3-9
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