Elenco 130-in-1 Electronics Playground - Manual (Page 12)

-149- -12-
Transistors are very important, and you may need to
test them to be sure they are working. You can’t tell if
one is working just by looking at it, but this circuit lets
you test them. This circuit also checks whether a
transistor is a PNP or an NPN.
You’ll notice that this project has three long wires - one
for the emitter, one for the collector and one for the
base. The schematic shows the terminals marked for
checking PNP transistors.
To use this experiment, connect the long wires to the
base, collector, and emitter of the transistor you want
to test. Turn the control fully counter-clockwise. Then,
press the key and turn the control clockwise. The
transistor is a working PNP transistor if you hear a
sound from the speaker. If you hear no sound at all,
change connections 4-124 and 119-138 to 4-119 and
124-138, and repeat the test. If you get a sound from
the speaker this time, the transistor is a working NPN
type. If you get no sound from the speaker using either
set of connections, the transistor is defective.
You’ll find this a handy circuit for testing unmarked
transistors as you start to accumulate parts for other
electronic circuits.
Notes:
EXPERIMENT #127: TRANSISTOR TESTER
Schematic
Wiring Sequence:
o 1-29
o 2-30
o 3-105-COLLECTOR
o 4-124
o 5-94-106-110
o 26-72-137
o 27-71
o 28-EMITTER
o 93-109-BASE
o 119-138
o 121-122
For your first experiment you are going to make a
circuit that that sounds like a woodpecker chirping.
Follow the wiring sequence carefully and observe the
drawings. Don’t forget to make all the proper
connections and have fun!
The simple circuit shown here does not have a key
or a switch, but you can easily add one. Replace
connection 124-28 with connections 124-137 and
138-28 to connect the key. Or, you can hook the
switch up by replacing 124-28 with connections 124-
131 and 132-28. Now you can easily turn off and on
the circuit. Go outside and see if you can attract birds
with it.
Want a different sound? Try varied combinations of
capacitance and resistance in place of the 100
μF
capacitor and the 1k
Ω resistor. To change the 100μF
capacitor to 470µF, disconnect terminal 116 and
transfer to terminal 118. Then, reconnect the wire
from 115 to connect to 117. Your “bird” might sound
like a cricket, or a bear!
Also, you can try using the 3V power supply.
Disconnect terminal 119 and connect it to terminal
123. Now your bird might sound like an English
sparrow. Feel free to experiment. Just don’t replace
the 47k
Ω resistor with anything below 10kΩ,
because it might damage the transistor.
Notes:
EXPERIMENT #1: WOODPECKER
Wiring Sequence:
o 1-29
o 2-30
o 3-104-106
o 4-28-124
o 5-41-105
o 27-88
o 75-87-103-40
o 115-42-119
o 76-116
o 121-122
Schematic