Simpson 650 - Theory of Operation

SECTION III
THEORY OF OPERATION
BETA MEASUREMENT
Basically, the Model 650 consists of a bridge
circuit in which balance occurs when the collector
current is 1 milliampere. The ZERO ADJ. control
adjusts the base current to achieve this 1 ma. of
collector current. At this point the meter current
is zero.
When the BETA range switch is in the 250, 50,
or 10 position, a pre-determined change of base
current
is
then
switched
into
the
circuit.
The
resulting bridge unbalance yields a meter deflec-
tion
which
directly
corresponds
to
Beta.
Beta
is
defined as
AL.
Al
B
with
Es
constant.
Despite
its
simplicity,
the
Beta
measuring
circuit
in
the
Model
650
is
unique
and
technically
dependable
(Patent
Pending).
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