Elenco Electronics EP-130 - Heat-Sensitive Oscillator

-
83
-
Did
you
k
now t
h
at a trans
i
stor a
l
ters
i
t
s
characteristics accordin
g
to the temperature
?
This
experiment will show you how temperature affect
s
trans
i
stor act
i
on.
Vi
e
w th
e
sc
h
e
m
a
ti
c
. Th
e
NPN tr
a
n
s
i
s
tor
ac
t
s
as
a
pulse oscillator. The 22k
Ω
resistor and the PN
P
transistor control the volta
g
e applied to its base. Th
e
trans
i
stor
’
s
b
ase current an
d
co
ll
ector current vary
with the temperature.
Build this experiment and
y
ou will hear a sound
f
rom
the speaker. Modi
f
y the 50k Ω control so that th
e
sound is low or a series o
f
p
ulses
.
Hold the PNP transistor between your
f
in
g
ers to
warm
i
t u
p
.
A
s t
h
e trans
i
stor tem
p
erature
i
ncrease
s
you w
ill
h
ear t
h
e tone
b
ecome
hi
g
h
er.
No
t
es
:
EXPERIMENT #65: HEAT-SENSITIVE OSCILLATO
R
S
chematic
W
iring
S
equence:

1
-2
9

2
-
30

3
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101
-
103

4-2
6
-41-11
9

5
-47-1
0
4

2
7-81

120
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28
-
48

40-82

42
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8
5

46-102-86