SAM-III Construction Manual
See last page for document and copyright information, File: SAM-III Magnetometer Construction.doc, Page 33
The output can be calibrated to provide a range of 0 to +5 V or –2.5 to +2.5 V. The SAM-III analog output
is proportional to K-index, so it is recommended that it be calibrated for a range of 0 to +5 V. If you do
not plan to use the analog output, this step can be skipped.
After the previous tests were done, the SAM-III displays the following text:
analog output
P1: gain P2: offset
F1 = OK F2 = 1/2Umax
F3 = Umax F4 = Umin
To set the output to a range of 0 to 5 V, press F3 (Umax)
P2
P1
Pin 1 of U11
Set the multimeter to the 20 Vdc range, and connect the meter negative lead to position 6 (ground) of
X1.
A. Press F3 (Umax). Connect the meter positive lead to pin 1 of U11 (LM358N op-amp). See illustration
above. Adjust P1 until the meter reads +5.00 V.
B. Press F4 (Umin). Connect the meter positive lead to position 5 of X1 (analog output). Adjust P2 until
the meter reads 0.00 V.
C. Press F3 (Umax). Adjust P1 until the meter reads 5.00 V. Repeat B. and C. adjustments until the
voltages do not change.
For a range of –2.5 V to +2.5 V, press F2 (1/2Umax).
Connect the meter negative lead to position 6 (ground) of X1. Connect the meter positive lead to pin 5
of X1. Adjust P2 until the meter shows 0.00 V. Repeat the previous adjustments until the voltages do not
change.
