Specifications
CONSTRUCTION
Fig. 5 (v)
Fig. 5 (iv)
vice uses the set-2 binary numbers for
identification of the collector (hence the
emitter), the same number (base-Id) ob-
tained during base identification cannot
be sent through port
C
, if the device un-
der test is of npn type. The base-Id found
must be
EX
-
OR
ed first with
OF
(
H
). Since
the base-Id found here is
02 (
H
), the data
to be sent through port
C
in this case
would be as shown in Table VI.
Note that
PC
3 becomes logic-1, which
would close switch
SW
4 to get the set-2
binary numbers.
Once resistor
R
5 is inserted in the base
circuit, and set-1 binary numbers are ap-
plied to the device (pnp type), it would be
biased sequentially in three distinct ways,
of which only two would be effective. The
same are shown in Fig. 2.
In case of binary number
100, the cur-
rent through the internal
LED
of
IC
4 would
distinctly be very low compared to the
current flowing during number
001,
through the internal
LED
of
IC
7. If
R
5 is of
sufficiently high value, the former cur-
rent may be reduced to such an extent
that the related
LED
would be off. Hence,
the data that would be formed at the emit-
ters of transistors
T
1-
T
3
would be 001. It would be
modified by the software to
0000 0001=01(H). This is
termed in the software as
emitter-Id and is stored at
memory location
216B.
On the other hand, if
the device is of npn type,
set-2 binary numbers are
to be applied to it, and the
transistor would be biased
as shown in Fig. 3. Here,
only the internal
LED
of
IC
4
would flicker. So, the data
at the output would be
100=04(H). This is termed in
the software as collector-Id,
and is stored in memory lo-
cation
216
C
. (In case of pnp-
device, the collector-Id is determined
mathematically by subtracting the Base-
Id from the emitter-Id.)
So the result could be summarised as:
pnp type:
Base-Id =
05(H), Collector-Id = 01(H).
npn type:
Base-Id =
02(H), Collector-Id = 01(H).
DISPLAY ROUTINE USING ALTERNATIVE CIRCUIT OF FIG. 4
TABLE V
PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0
00000101
TABLE VI
PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0
00001101
With this result, the software would
point to configuration
CBE
in the data
table, and print the same on the display.
By a similar analysis, lead configuration
for any other orientation of the device in
the test socket would be displayed by the
software, after finding the related base-
and collector-Id.
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