Instruction manual

HB 01-26-09 Oscilloscope (1) Lab 5 8
When this control is in the CAL position, control 23 is calibrated. Set in CAL position (fully
clockwise).
27. HORIZONTAL POSITION/PULL control. Adjusts the horizontal position of the trace.
Set pointer up. This control knob can be pulled out to expand the trace horizontally. Set
the knob in.
29. X-Y button. This button should be out. (button is “in” for x-y operation.)
30. HOLDOFF/PULL CHOP control. Check that this knob is in and full counterclockwise.
31. Trigger SOURCE switch. Selects the signal from which the trigger pulse is derived. Set
at CH 1 (CH=channel).
32. Trigger COUPLING switch. In the AUTO mode, a sweep voltage is generated and a
trace appears whether or not there is an appropriate signal for the scope to trigger on. In
the NORMAL mode, a trigger pulse and trace are only generated if the input voltage has a
value that satisfies the trigger voltage level chosen. With a strange scope it is often difficult
to find a trace. For this reason, set this control at AUTO.
33. TRIGger LEVEL/PULL(-)SLOPE. Adjusts the trigger level voltage, V
T
. Set knob
pointer up, which is approximately V
T
= 0. When knob is in, scope triggers on positive
slope of signal. When knob is out, scope triggers on negative slope of input signal. Set knob
in for positive slope triggering.
34. External Trigger. The connector at which an external trigger signal is fed into the scope.
Not used in this lab.
6 Using The BK Oscilloscope
In this section the BK scope is used to examine various AC voltages. You will be able
to “see” how the voltage depends on time, measure the amplitude at various times, and
measure times between different points on the voltage vs time curve. It will probably be
helpful to refer to previous sections during these exercises. Reminder: the VOLTS/DIV and
TIME/DIV switches are not calibrated unless the knobs in the center of these switches are
fully clockwise in the calibrated positions.
6.1 Preliminaries
Remove any input cables to the scope. Turn on the scope (control 3) and observe LED (1).
In a few seconds you should see a trace which is a horizontal line (it takes the cathode a
few seconds to warm up). If you do not, check your initial control settings. Adjust the
INTENSITY (4) and FOCUS (6) controls for a sharp trace which is easy to view but not
brighter than necessary. Too bright is hard on the phosphor. Move the trace about the
screen with the 2 POSITION controls, 17 (vertical) and 27 (horizontal). Leave the trace
centered. Turn the time base switch (23) to 0.2 s and note the light spot move slowly across
the screen until it gets to the right hand side of the screen. What happens then? Investigate