Elenco Electronics EP-130 - Audio Continuity Tester

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143
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This circuit emits a sound if the material you are
checkin
g
transmits electricity. This is convenient whe
n
you are
l
oo
ki
ng at w
i
res, term
i
na
l
s, or ot
h
er t
hi
ngs an
d
cannot look at a signal lamp or LED. Your ears wil
l
detect the results of the test while your eyes are busy.
If the component or circuit you are testin
g
conduct
s
electricity, it will complete the circuit for a pulse-typ
e
oscillator. You can use this to test most o
f
th
e
com
p
onents in this kit. For diodes and transistors
,
remember that electricity only
f
lows through them i
n
one direction (unless they are dama
g
ed).
In the schematic, you will see that the output
f
rom th
e
transistor
g
oes throu
g
h the trans
f
ormer to the 0.02
μ
F
ca
p
acitor and then to the base o
f
the transistor. Th
e
TE
S
T terminal is connected to the emitter of the
transistor. The transistor starts to oscillate when
s
omethin
g
that allows electricity to
f
low is connecte
d
to the terminal.
You can sa
f
el
y
check almost an
y
component with this
continuit
y
checker because it uses a ver
y
low curren
t
o
f
about 15mA or less. You mi
g
ht want to try
measurin
g
the continuity o
f
pencil lines on paper,
water, metallic sur
f
aces, and many other thin
g
s
.
No
t
es
:
EXPERIMENT #121: A
U
DI
O
CO
NTIN
U
ITY TE
S
TE
R
Schematic
W
iring Sequence:

1
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29

2
-30

3-103-109

4
-87-120

5
-
110
-
41

88
-
104
-
40

4
2-116-PROBE
S

1
1
5
-1
3
1-PR
O
BE
S

119
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132