Scientific 5000 Series, Manual

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APPENDIX L
MODEL 5000 SERIES MANUAL
Version 1.23
13-57
Appendix L
Quadrac/Diac Adaptor (ADP-350)
V
BO
/ I
BO
tests
A stepped voltage ramp is applied at the adaptor G terminal through a resistor in
three tiers, each with increased resolution. Each ramp is composed of at least 64
discrete steps. The trigger voltage is measured at each step using a high speed A/D
converter and recorded to determine the maximum trigger voltage (V
BO
) for each of
the three ramps.
The first ramp determines an initial V
BO
value. The second ramp begins just below
this first V
BO
value and a second V
BO
, at finer resolution, is determined. The third
ramp, using the second V
BO
value determines the final, high resolution, answer. This
triple ramp method is fast, requiring approximately 25 milliseconds, and accurate,
using a 14-bit resolution A/D converter.
I
BO
is computed by using the V
G
that occurred at V
BO
. The applied V
G
is recorded at
each step just as the trigger voltage was to determine V
BO
. I
BO
is computed using the
equation: I
BO
= (V
G
– V
BO
)/200K
Ω. This computation is made in a subsequent test
step in real time.
Figure 13-43 Quadrac/Diac V
BO
Test
ΔV
BO
Symmetry is obtained using a real-time math step to compute the absolute difference
in the positive and negative V
BO
at VBO
Final VBO
Applied V
(bi-direc tional)
Measured V
80V
V
G
Initial VBO
G
GS