Tektronix 2225, Operator'S Manual

Page: 41 / 79

Applications
9. Calculate the instantaneous voltage, using the following
formula:
Instan- vertical polarity VOLTS/DIV
taneous = deflection x ( + o r - ) x setting
Voltage (divisions) (1 OX PROBE)*
*lf a IX probe is being used for the measurement, use the IX
VOLTS/DIV setting.
EXAMPLE. In Figure 3-2, the measured vertical deflection from
the reference line is 4.5 divisions, and the waveform point is above
the reference line. A10X attenuator probe is being used, and the
VOLTS/DIV switch is set to 2 V (10X PROBE).
Substituting the given values.
Instantaneous Voltage = 4.5 div x ( + 1) x 2V/div = 9.0 V.
Algebraic Addition
With the VERTICAL MODE switches set to BOTH-NORM-ADD,
the waveform displayed is the algebraic sum of the signals
applied to the Channel 1 and Channel 2 inputs (C H 1 + CH 2). If
the middle MODE switch is then set to CH 2 INVERT, the wave­
form displayed is the difference between the signals applied to
the Channel 1 and Channel 2 inputs (CH 1— CH 2). When both
VOLTS/DIV switches are set to the same deflection factor, the
deflection factor of the ADD trace is equal to the deflection factor
indicated by either VOLTS/DIV switch.
The following general precautions should be observed when
using ADD VERTICAL MODE.
1. Do not exceed the input voltage rating of the oscilloscope.
2. Do not apply signals whose peaks exceed the equivalent of
about ±
8
times the VOLTS/DIV switch settings, since large
voltages may distort the display. For example, with a VOLTS/
DIV setting of 0.5 V, the voltage applied to that channel should
not exceed approximately 4 V.
3. Position the Channel 1 and Channel
2
waveforms near center
screen, when viewed separately. This ensures the greatest
dynamic range for ADD mode operation.
4. To attain similar responses from both channels, set the Chan­
nel 1 and Channel 2 input coupling switches to the same
position.
3-4
2225 Operators