©IPK22/10/00
NAME:......................................................................
DATE ISSUED:........................................................
COMPLETION DATE:............................................
FEEDBACK:
ELECTRONICS
INDUCTION
PACKAGE
TO BE COMPLETED BY ALL STUDENTS
STARTING THE ELECTRONICS COURSE.
PART 1
(1).
(2).
(3).
PART 2
(4).
(5).
(6).
(7).
Basic safety.
Using a Protoboard.
A Basic Water Alarm.
A Basic Timer.
How to Solder including - The Soldering Test.
Using Strip board.
A Logic Probe.
©IPK22/10/00
A).(1).
*Basic safety.
Read through the following passage and then complete the tasks below.
Most of what you do in electronics is completely safe, but you should take great care when
SOLDERING, when using CUTTING TOOLS and when using MAINS POWER.
A hot soldering iron or hot solder can give a nasty burn. They typically will have a temperature
between 200oC and 400oC. It can also burn through clothes and books. Soldering irons never look
HOT and so you should always handle a soldering iron as if it was HOT.
It should always be kept in a soldering iron holder when it is not actually being used for soldering.
A soldering iron should never be left lying on a bench. The heat from a soldering iron can easily
melt plastics. A soldering iron should be kept away from plastic cases, plastic components and the
insulation of wires, especially the leads of mains powered equipment. Melting the insulation on
mains cables is extremely dangerous.
Work carefully so that there is no chance of hot solder getting into eyes or onto skin or clothes.
Wear goggles of safety glasses.
All burns are painful and should be immersed in cold water. Skin which has not blistered will be
very sore for a few hours but will heal within a few days. Skin which has blistered will also be very
sore and will take much longer to heal. Blisters should not be burst but should be allowed to heal
naturally. If the skin has blisters which have burst then medical advice must be sought.
All cutting tools, by definition, must be sharp! Tools designed for cutting metals will have little
trouble cutting skin! Take special care when cutting wire with wire clippers since the pieces of wire
could fly off into someone's eye. Take special care when cutting aluminium sheet since the edges
can be very sharp. Use a file to remove all sharp edges. Take special care when drilling holes.
Wear goggles or safety glasses to protect your eyes from swarf and also if the drill breaks. Ensure
that what is being drilled is held down firmly and does not start to spin round with the drill. Use a
large drill or a file to remove burr from holes drilled in metal sheets.
Ensure that:
(a)
any mains powered equipment is used well away from any water or other liquids. Check
that the plug and the mains cable are not damaged before connecting to the mains,
(b)
you do not place circuit boards or test equipment near the edge of a bench where they could
easily be knocked onto the floor,
(c)
there are no cables placed across access ways that could cause someone to trip.
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Tasks
1).
Of the many safety issues covered in the passage above, list the five that you consider to be
the most serious and explain your choice.
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2).
State two safety issues that you feel students should consider when working with electronics
and explain your choice.
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©IPK22/10/00
A).(2).
Using Protoboard.
The best way to learn electronics is to build circuits and investigate how they operate. To enable
circuits to be built quickly, Push-In or Solderless Breadboards have been developed. These often
have many different commercial names and shapes but they all work on the same principle, that of
the wires of the components being pushed through holes in a plastic case and held tightly by a metal
spring. The general name used for all of these boards is PROTOBOARDS.
The layout of a typical protoboard is shown in the diagram below.
1
5
10
15
20
25
A
A
B
C
B
C
D
E
D
E
F
F
G
H
I
G
H
I
J
J
1
5
10
15
20
25
Each hole on the board will accommodate one wire. The lines show which holes are joined together
by the metal springs. The holes in the main body of the protoboard are joined vertically, with a gap
in the middle to accommodate integrated circuits. The holes at the top and bottom of the board are
joined horizontally and can be used as power supply lines.
The first circuit that you are going to build uses a RESISTOR and a LIGHT EMITTING DIODE,
which is usually referred to as a LED.
Resistors.
A resistor is a component that reduces the amount of electric current that flows.
Use the Support Booklet and any practical equipment that you need to carry out the following tasks.
1).
Examine a selection of resistors and draw sketches to show what they are like.
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2).
Draw a labelled diagram to show the cross section of a resistor.
3).
All electronic components are represented by symbols since they are easier to draw than
pictures. Draw the symbol that is used to represent a resistor.
4).
Name three types of resistors and describe their differences, advantages and disadvantages.
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5).
What is the unit of resistance?
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6).
Explain what is meant by a PREFERRED VALUE.
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7).
Explain what is meant by the tolerance of a resistor.
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©IPK22/10/00
8).
The value of a resistor is often marked onto the resistor using coloured bands. What would
be the value of a resistor having a yellow, a purple, a brown and a gold band?
This is the resistor that you will need for the practical work.
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Light Emitting Diode or LED.
A LED is a small semiconductor component that will emit light when an electric current passes.
1).
Examine a LED and draw a sketch. Remember to show one lead longer than the other and
also the small flat part on the one side of the body.
2).
Draw the symbol for a LED.
3).
How many volts are needed across a LED to make it light?
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4).
How much current should flow through a LED?
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5).
State three uses of LEDs.
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6).
What are the advantages of LEDs compared to normal lamps?
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Practical Work.
+9V
1).
The diagram of the circuit that you are going to construct is shown
opposite. Label the components.
470 
2).
Collect a protoboard, LED and a correctly coloured resistor.
Decide how you are going to arrange them on your protoboard to
construct the circuit.
DO NOT pull the leads of the LED too far apart, or they will break!
Use a battery connector to connect your circuit to a 9V battery.
Ensure that your circuit is correct before connecting it to the 9 volt
power supply.
Mark onto the diagram of the protoboard where you have inserted the components.
1
5
10
15
20
0V
25
A
A
B
C
B
C
D
E
D
E
F
F
G
H
I
G
H
I
J
J
1
5
10
15
20
25
3).
If all is well the LED should light. If it does not check your work.
4).
What happens if the power supply is connected the other way round to your circuit?
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5).
Explain the purpose of the resistor.
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©IPK22/10/00
A).(3).
A Basic Water Alarm.
This assignment introduces Integrated Circuits, (ICs). An IC consists of a tiny piece of silicon onto
which complex circuits are fabricated directly. Putting circuits into IC form has many advantages,
the main one for the user is that very complex circuits can be constructed quickly by using ICs as
building blocks.
The IC used in this assignment is a digital circuit. It contains six separate NOT gate circuits and it
is one of these that will be used for the Water Alarm. The serial number of the IC is 4049UB.
The IC has 16 pins for connections.
The diagram below shows the connections to the pins of the IC looking down from the top.
NC
NC
4049UB
1
+Vs
0V
NC means that there is No Connection to that pin (terminal).
+Vs is the positive connection and 0V is the negative connection to the power supply/battery.
The symbol for a NOT gate is
input
output
Each of the NOT gates of the IC are identical, so any can be used for the following circuits.
However, the NOT gates are easily damaged by static electricity and so ALL of the unused inputs
should be connected to 0V connection to the battery.
For the circuits that follow, the IC should be carefully placed across the centre of your protoboard,
as in the diagram below.
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5
10
15
20
25
A
A
B
C
B
C
D
E
D
E
4049UB
F
F
G
H
I
G
H
I
J
J
1
5
10
15
20
25
The protoboard, resistor and LED were introduced in the last assignment. This assignment
introduces the NOT gate, which is an ACTIVE component (i.e. it can amplify). Using the NOT
gate you will build a circuit that can act as a Water Level Alarm.
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It is customary not to mark the power supply connections to the IC on the circuit diagram but to
assume that they are connected.
DO NOT FORGET TO MAKE THESE CONNECTIONS
WHEN CONSTRUCTING YOUR CIRCUITS
Label the components in the circuit diagram below.
+9V
A
R2
Input wire
R1
0V
1).
R1 is a 1M, 5% resistor. Write down the coloured bands that the resistor will have.
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2).
R2 is a 470, 5% resistor. Write down the coloured bands that the resistor will have.
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3).
Draw on the protoboard diagram below (in pencil) an arrangement for how the components
can be arranged to construct the circuit. You can use any of the NOT gates in the IC, but remember
to connect all of the unused inputs to 0V. Check the design with your supervisor before continuing.
1
5
10
15
20
25
A
A
B
C
B
C
D
E
D
E
F
F
G
H
I
G
H
I
J
J
1
5
10
15
9
20
25
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4).
Collect the components and carefully construct the circuit on a protoboard, following your
design on the planning sheet. Use single core wire for making other connections on the
protoboard.
Check the design with your supervisor before continuing.
5).
Connect a 9V battery to the circuit.
Ensure that the positive wire (RED) is connected to the positive terminal and the negative
wire (BLACK) to the negative terminal.
Switch on. What happens?
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6).
Connect another piece of wire to the positive line and touch the free end onto the free end of
the INPUT wire.
Switch on. What happens this time?
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7).
Fetch a beaker of water and touch the free ends of the two wires into the water.
Explain what happens this time. Use the support booklet to help you.
What is the NOT gate acting as?
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8).
Explain how this circuit could be used as a water level alarm to prevent a bath being
overfilled.
How could you improve this basic circuit?
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©IPK22/10/00
A).(4).
A Basic Timer.
This task is to give an introduction to capacitors and their use in electronic timing circuits.
Use the Support Booklet and any practical equipment that you need to carry out the following tasks.
The Capacitor.
1).
A capacitor stores electric charge (electricity).
Examine a selection of capacitors and draw and label sketches to show the different types.
2).
Draw a labelled diagram to show the construction of a capacitor.
Draw the symbols that are used to represent capacitors.
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3).
What is the unit of capacitance?
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4)
(a)
The two main types of capacitor available are Polyester and Electrolytic.
What are the differences between them?
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(b)
What special care must you take when using electrolytic capacitors?
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(c)
The circuit diagram for the timer is shown below. Label the components.
+9V
A
R2
Input wire
+
R1
C
0V
5).
On a protoboard diagram below draw (in pencil) an arrangement for how the components
can be arranged for the circuit of the timer shown above.
Check your design before continuing.
1
5
10
15
20
25
A
A
B
C
B
C
D
E
D
E
F
F
G
H
I
G
H
I
J
J
1
5
10
15
12
20
25
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6).
R1 is a 10k resistor. What coloured bands does it have?
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R2 is a 470 resistor. What coloured bands does it have?
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C is a 100F electrolytic capacitor. Ensure that it is connected the correct way round.
Collect the components and carefully construct the circuit on a protoboard by following
your design on the protoboard diagram. Use single core wire for making other connections
on the protoboard. Check your design before continuing.
7).
Connect a 9V battery to the circuit.
Ensure that the positive wire (RED) is connected to the positive terminal and the negative
wire (BLACK) to the negative terminal.
Switch on. What happens?
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8).
Connect the input wire onto the positive supply line. What happens?
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Now disconnect the input wire from the positive supply line. What happens?
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How long does the LED remain lit after the input wire has been disconnected?
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9).
Replace the 10k resistor with a 100k resistor. What coloured bands does it have?
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How long does the LED remain lit after the input wire has been touched onto the positive
supply line?
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10)
Replace the electrolytic capacitor with a larger value. Note the value of this larger capacitor
and also how long the LED remained lit after the input wire had been disconnected from the
positive supply line.
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11).
Use the Support Booklet to explain how the circuit is working as a timer.
What is the purpose of the capacitor in the circuit?
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13).
Explain how such a circuit could be used as an Egg timer.
Find out how long an egg should be boiled for.
Suggest values for the capacitor and input resistor, R1, that will give this time.
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A).(5).
How to Solder.
Read through the paragraphs below and then answer the questions.
Successful soldering
Soldering is a technique that is employed in
electronics to provide reliable, low resistance
connections between wires and components. Solder
is not intended to be a type of glue or a filler
(although it will actually do these jobs quite
successfully.) Solder is an alloy (mixture of two or
more metals) made from tin and lead in the ratio of
3:2. It melts at a temperature of approximately
200oC and will make good connections to copper,
brass, tin, silver and gold.
solder
flux
The solder used for electronic work comes as soldering wire in two main sizes, 18 SWG or
22 SWG. As well as the solder it also contains a flux which helps the solder to flow more readily
onto the metal surfaces. A diagram showing the cross section of solder is shown in figure opposite.
The flux melts along with the solder and appears as a 'smoke'. This 'smoke' should not be inhaled
since it can cause respiratory irritations.
For metals to be soldered they must be clean and free from any grease or corrosion. A soldering
iron suitable for modern electronics work will have a power rating of 15W and a small 'bit' with a
diameter of 2mm to 4mm. The bit is made from copper and is coated with tin. It will reach a
temperature of up to 350oC and, in normal use, will last a long time. It will become coated with
black material (often copper oxide or burnt grease) and should be cleaned by being wiped with a
damp sponge.
The tip of the bit of the soldering iron should be kept coated with a thin layer of solder and so after
it has been cleaned it should be touched onto the soldering wire to coat it. This process is known as
tinning.
For two metals to be joined by solder it is important to ensure that both metals and the solder are at
a temperature above which the solder melts.
Soldering wires to terminal connections
The wire is passed through the hole in the terminal. It should not be
wrapped around the terminal unless you are absolutely certain that you soldering iron
will never want to remove it again!
The bit of the soldering iron should be placed against the terminal and
the wire until they are hot enough to melt solder (two or three seconds)
and then solder should be applied. If all is at the right temperature then wire
bit
the solder will be seen to melt and flow onto the wire and terminal.
Sufficient solder should be used to completely cover the terminal hole
terminal
and the wire where it passes through the terminal. When this has
happened, the solder wire should be removed and then the soldering iron should be removed. It will
take a few seconds for the metals to cool sufficiently for the solder to freeze, but it could remain hot
enough to cause burns for several minutes afterwards.
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Soldering wires to circuit boards
A similar process is used to that for soldering to terminal
connections. The wire is passed through the hole in the
circuit board. The bit of the soldering iron is placed against
the circuit board copper and the wire for one or two seconds
and then solder is applied to the bit of the iron. If all is at the
right temperature then the solder will be seen to melt and
flow onto the wire and the circuit board copper. Sufficient
solder should be used to completely cover the circuit board
hole and the wire where it passes through the hole. When
this has happened, the soldering wire should be removed and
then the soldering iron should be removed. It will take a few
seconds for the metals to cool sufficiently for the solder to
freeze, but it could remain hot enough to cause burns for
several minutes afterwards.
soldering iron
circuit board copper
wire
bit
circuit board
Common soldering faults
1).
Symptom:
Cause:
Remedy:
The wire is coated with solder but the circuit board copper is not.
The soldering iron did not warm the copper of the circuit board
sufficiently.
Reheat the copper board and the wire and apply some more solder.
2).
Symptom:
Cause:
Remedy:
The circuit board copper is coated with solder but the wire is not.
The soldering iron did not warm the wire sufficiently.
Reheat the circuit board copper and the wire and apply some more
solder.
3).
Symptom:
The wire appears to be soldered correctly but it has formed a high
resistance joint.
This is known as a DRY JOINT and is caused either by dirt on the
wire or the wire not being heated sufficiently.
Reheat the copper board and the wire and apply some more solder.
If the joint still has a high resistance then the wire should be removed
and cleaned before being re soldered.
Cause:
Remedy:
The timing for soldering components, especially semiconductors, is very important. If the wire and
circuit board are not adequately heated then a poor joint will result. If the wire and circuit board are
heated too much then there is a great danger of damaging the component.
Semiconductor devices will usually withstand the heat of a soldering iron for about 2 seconds.
Quick, careful and effective soldering is vital. If you are uncertain how quickly you will be able to
solder a delicate (or expensive) component, a Heat Shunt should be used to conduct the heat away
from the component. A pair of small nose pliers will act as a convenient heat shunt for components
with leads, eg transistors. The lead being soldered is held with the pliers. Excessive heat is then
conducted to the pliers instead of the transistor.
Solder should NEVER be applied to the bit of the soldering iron and then transported to the wire
and circuit board copper. At the best, the solder joint will be of very poor quality because the flux
needed to help the solder flow will have burnt off from the soldering iron while the molten solder
was being transported. Solder should only be applied to the hot wire and copper when they have
been heated by the soldering iron.
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1).
What is solder made from?
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2).
At what temperature does solder melt?
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3).
Name three metals that can be soldered.
4).
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Suggest a reason why the surfaces to be soldered must be cleaned if they are greasy or
corroded.
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5).
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How should the soldering iron bit be cleaned if it is dirty?
Why should you never file the soldering iron bit to clean it?
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6).
Explain, in your own words, how to solder a wire onto a piece of copper. Draw diagrams to
help if you wish.
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7).
Suggest a reason why it is necessary to ensure that solder has flowed onto both of the
surfaces to be joined?
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8).
What happens to the components being soldered if heat is applied to them for too long?
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9).
What is a HEAT SHUNT and how is it used?
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10).
What components are most likely to suffer damage from excess heat?
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11).
Why should work that has been freshly soldered not be touched.
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12).
Explain briefly why wearing goggles or safety glasses is a sensible safety precaution when
soldering.
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13).
Explain briefly what you should do if you burn yourself with a soldering iron?
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14).
Explain why hot soldering irons should not be left lying on a bench but should be returned
to a soldering iron stand.
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A).(6).
Stripboard and the Soldering Test.
STRIPBOARD.
While protoboards provide a very quick means of assembling and testing circuits, they do not
provide a reliable circuit for normal use. Printed circuit boards provide the most reliable means of
ruggedly constructing circuits but the design of the circuit board can take a long time and is not
easily modified. A more convenient way to produce rugged and reliable circuits is to use
stripboard. The diagram below shows a piece of stripboard viewed from the bottom.
It consists of a sheet of SRBP board punched with holes every 0.1 inch and with strips of copper
foil running horizontally. These copper foil tracks are used to make connections between the
components by soldering the components to the copper tracks.
In use, the components would be placed on the TOP side of the board with the wires poked through
the holes. The wires are then soldered to the copper track and the excess wire removed.
THE SOLDERING TEST.
Since the strips on stripboard are only 0.1 inches apart it is very easy to spread solder from one strip
to another. This causes short circuits and is of little use. This test is to give you practice at
soldering to strip board.
Obtain an offcut of strip board and solder six wires to adjacent copper strips along the edge of the
board. Seek assistance from your supervisor if you have difficulty with this task.
When completed have your work assessed by your supervisor and attach the sample to your
Induction Booklet.
Supervisor Signature:.........................................................................................................................
Date:...................................................................................................................................................
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A).(7).
The Logic probe.
In this section you are going to make a Logic probe for use with the next section of work.
A Logic Probe is used to indicate the logic state of a point in a circuit. If the voltage at the point is
greater than half of the supply voltage a red LED will light and if it is less than half of the supply
voltage a green LED will light. If it is not connected then neither of the LEDs will light.
The circuit diagram for the Basic Logic Probe is shown below together with a strip board layout.
Examine the circuit diagram and layout carefully. It is very difficult to correct errors if you make
mistakes.
10R
470R
+
pin 1
High
red
+Vs
10F
1N4001
470k
5
probe
100k
1M
4
4049UB
1M
7
6
green
Low
pin 8
470R
0V
red
+
+
4
7
0
R
probe
1
0
R
4049UB
470k
100k
+
green
1
M 1
4
M
7
0
R
+
10F
_
1N4001
10 strips by 24 holes
Collect all of the components that you need, including the piece of strip board and fit the
components onto the circuit board EXACTLY as shown in the diagram above. Check your layout
with someone else to ensure that it is correct.
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©IPK22/10/00
When you are certain that all of the components are correctly located carefully break the copper
track of the strip board as shown in the diagram, using a Strip Cutting tool.
Carefully solder all of the components in place.
Attach a thick piece of wire to form a probe and some twin wire to supply the power. Connect
crocodile clips to the free end of the power cable.
Attach your battery to the power cable and check that no LEDs light. If they do check your wiring.
Touch the probe to the positive terminal of the battery, the RED LED should light. If it does not,
check your wiring.
Touch the probe to the 0V terminal of the battery, the GREEN LED should light. If it does not,
check your wiring.
When you are satisfied that your Logic Probe is working correctly demonstrate its function to your
supervisor.
Supervisor signature…………………………………………….Date……………………..
If you have insufficient time to add the pulse detector then you should add wires to connect:
pin 3 to pin 1,
pin 14 to pin 16,
pin 9 to the bottom strip of the board.
This will ensure that all of the unused inputs are connected safely.
Ensure that your logic probe still works.
Make a list of the components that you have used and then, using component catalogues, calculate
the cost of your logic probe.
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©IPK22/10/00
PULSE DETECTOR
Sometimes a logic circuit will generate very short voltage pulses that can be a nuisance. The pulse
detector will make these visible by making a yellow LED flash when there is a high to low, or low
to high change of voltage on the logic probe input. The complete circuit diagram is shown below,
including the basic probe circuit.
10R
470R
+
10F
pin 1
High
red
probe
100k
1M
1N4001
4049UB
470k
5
+Vs
4
100k
1M
1N4148
2
3
7 6
green
Low
100nF
11
10
9
15
14
470R
12
yellow
pulse
1M
pin 8
470R
0V
yellow
1N4148 1N4148
red
+
+
4
7
0
R
probe
+
1
0
R
4049UB
470k
100k
+
green
1
M 1
4
M
7
0
R
1
M
1
0
0
K
4
7
0
R
+
10F
_
100nF
1N4001
10 strips by 24 holes
List the additional components that you need.
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©IPK22/10/00
Collect these components and carefully add them to your circuit board.
Make all of the additional strip breaks that are required.
Carefully solder the components onto the board. Check for errors.
When it is completed connect your battery to the power wires. No LEDs should light.
Touch the probe onto the positive terminal of the battery. The red LED should light and the yellow
LED should flash.
Touch the probe onto the 0V terminal of the battery. The green LED should light and the yellow
LED should flash.
When it is working correctly, demonstrate the probe to your supervisor.
Supervisor signature…………………………………………….Date……………………..
Calculate the additional cost of the components for the pulse detector, remembering that you do not
need another IC.
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