Keithley 486 Instruction Manual page 77

SECTION 3
Front Panel Operation
8.
9.
10.
B.
C.
D.
E.
rotary knob to display an interval of l/2 seconds
as follows:
TRIG
INTVL 000.500
Enter the displayed trigger interval by pressing
SHET and then SETUP.
Press hD3VU and use the rotary knob to display
the following message:
DATASTORE YES
Press MENU and use the&md, keys to display
a buffer size of 50 readings as shown:
BUFFERSIZE
0.50~0~s
Arm the data store by pressing MENU. The
"data store armed" indicator (9 wilI be dis-
played.
NOTE
When triggered, the data store will store 50
readings at an interval rate of l/2 seconds.
This will give you approximately 25 seconds
to move the LED gradually from the dark en-
vironment to a bright light sowce (lamp or
flashlight).
To start the data storage process, press the flashing
TRIGGER kev.
After allowing a few seconds to acquire readings in
the dark environment, gradually move the LED
fromthedarktowardsabrightlightsouxe.Timethe
transition from dark to bright light such that the last
few seconds of data storage are performed at peak
light conditions.
Data storage will be complete when the displayed
"W' turns off.
11. Perform the following steps to recall stored data:
A. Press and release MENU until the following
message is displayed:
DATARJXL
NO
5. Use the rotary knob to display the following
message:
DATARECL Y?Z?
C. Press MENU. The first reading (at memory loca-
tion 001) will be displayed. Since this measure-
ment was performed in the dark, the following
reading could result:
0.00074 Illi Lot 001
D. Examine the readings stored in the other mem-
ory locations by using the rotary knob. Turning
the knob clockwise increments the memory loca-
tions. Turning the knob counter-clockwise past
location 001 displays the minimum and maxi-
mum readings stored in the buffer. For this test,
the following maximum and minimun readings
could result
022.106 nA
LCChJAX
-0.36250 nA LOClV5V
12 To disable data recall, press SHIET and then MENU.
For this example, you would expect the current to in-
crease as the source of light increases. In general, the test
data should support this. However, because this test was
not conducted under ideal conditions, electric fields due
to a lack of shielding and induced currents due to cable
flexing when moving the LED most likely caused some
"undesirable" readings.
3-28