Owner manual
-
149
-
Transistors are very important, and you may need to
test them to be sure they are workin
g
. You can’t tell if
one
i
s wor
ki
ng
j
ust
b
y
l
oo
ki
ng at
i
t,
b
ut t
hi
s c
i
rcu
i
t
l
et
s
you test them. This circuit also checks whether
a
tr
a
n
s
i
s
tor i
s
a
PNP or
a
n NPN.
You’ll notice that this project has three lon
g
wires - on
e
for the emitter
,
one for the collector and one for th
e
base. The schematic shows the terminals marked
f
o
r
checkin
g
PNP transistors.
To use this experiment, connect the long wires to th
e
base, collector, and emitter o
f
the transistor you wan
t
to test. Turn the control
f
ully counter-clockwise. Then
,
press the key and turn the control clockwise. Th
e
transistor is a working PNP transistor i
f
you hear a
s
ound
f
rom the speaker. I
f
you hear no sound at all
,
change connections 4-124 and 119-138 to 4-119 an
d
124-138, and repeat the test. If you
g
et a sound from
t
h
e spea
k
er t
hi
s t
i
me, t
h
e trans
i
stor
i
s a wor
ki
ng
NPN
type. If you get no sound from the speaker using eithe
r
s
et of connections
,
the transistor is defective
.
You’ll
f
ind this a handy circuit
f
or testin
g
unmarked
transistors as you start to accumulate parts
f
or othe
r
electronic circuits
.
No
t
es
:
EXPERIMENT #127: TRAN
S
I
S
T
O
R TE
S
TER
Schematic
Wiring Sequence:
1-29
2-30
3-105-COLLECTOR
4-124
5-94-106-110
26-72-137
27-71
28-EMITTER
93-109-BASE
119-138
121-122