Project 1.1.8 Soldering Practice: Fun Light
Introduction
Regardless of whether you have your driver’s license or will soon be getting it, two absolute
certainties exist. One: you will want to drive your parents’ expensive car, and two: they will
not let you. To a parent, the reasoning is obvious. When you are first learning to drive, you
are most likely to make a mistake. Wouldn’t it be better to make these mistakes in the tenyear-old family minivan?
Like driving, good soldering requires practice. In this activity you will practice your soldering
skills while constructing a simple Fun Light Project. This Fun Light Project has many of the
same components as the Random Number Generator that you will construct in a future
activity. Moreover, like the old minivan, if you happen to damage the Fun Light while honing
your soldering skills, it’s not a big deal.
Equipment
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Vise
Safety glasses
Solder sucker and/or solder wick
Solder tool
Diagonal cutters
Needle nose pliers
Solder
Damp sponge
Soldering iron
Fun Light kit
9V battery
© 2014 Project Lead The Way, Inc.
Digital Electronics Project 1.1.8 Soldering Practice: Fun Light – Page 1
Parts List – Fun Light
Qty
Item
Symbol
Pictorial Diagram
(on PCB)
1
P.C.
Board
PCB
2
Resistor
10M Ω
(Brown,
Black,
Blue)
R1, R2
1
Resistor
100K Ω
(Brown,
Black,
Yellow)
R3
1
Capacitor
0.1µF
(104)
C2
8
LED Red
L1 – L8
Watch
polarity
Anode =
(+) = long
lead
Cathode =
(-)=
short lead
© 2014 Project Lead The Way, Inc.
Digital Electronics Project 1.1.8 Soldering Practice: Fun Light – Page 2
1
IC Socket
(16 pin)
U1
Watch for orientation of cutout – match to illustration
on PCB.
1
IC CD4094 (16
pin)
Assemble to socket AFTER socket has been
soldered – be careful because the prongs bend
easily. Match the “dimple” with the cutout on the
socket.
1
IC Socket
(8 pin)
U2
Watch for orientation of cutout – match to illustration
on PCB.
1
IC NE-555
(8 pin)
Assemble to socket after socket has been soldered –
be careful because the prongs bend easily. Match
the “dimple” with the cutout on the socket.
1
9V Battery
Connector
9V
Solder the red wire to the (+) hole and the black wire
to the (-) hole. Thread wire from the foil side through
hole A and down the component side through hole
B.
© 2014 Project Lead The Way, Inc.
Digital Electronics Project 1.1.8 Soldering Practice: Fun Light – Page 3
2
Velcro
piece – 1”
Attach one strip to the battery and the other to the
foil side of the PCB.
1
9V
Battery
(not
included
in kit)
Connect to battery connector. Unplug battery when
light is not being used.
Assembly Procedure
1. Insert and solder (one at a time) the 10MΩ (brown, black, blue, gold) resistors into
locations R1 and R2. Insert the resistors through the component side and solder on
the foil side. Bend the resistor leads over so the component is secure during
soldering. Have your instructor check your soldering work at this time. Trim excess
lead length with diagonal cutters.
© 2014 Project Lead The Way, Inc.
Digital Electronics Project 1.1.8 Soldering Practice: Fun Light – Page 4
2. Insert and solder the 0.1µF capacitor into location C2. Insert the capacitor through
the component side and solder on the foil side. Bend the capacitor leads over so the
component is secure during soldering.
3. Insert and solder the 100KΩ (brown, black, yellow, gold) resistor into location R3.
Insert the resistors through the component side and solder on the foil side. Bend the
resistor leads over so the component is secure during soldering.
4. Insert and solder the 16 pin and 8 pin sockets into locations U1 and U2 respectively.
Check to make sure the socket is assembled with the cutout on the left side according
to the diagram on the PCB. Do NOT assemble the ICs to the sockets at this time.
5. Insert one LED into the L1 location. Make sure the LED is assembled correctly with
the anode (longer lead) into the (+) location and the cathode (shorter lead) into the (–)
location. Insert and solder all remaining LEDs similarly in locations L2 – L8.
6. Insert and solder the two battery connector leads. The red lead is threaded up
through the foil side at Hole A and through the component side hole marked (+).
Similarly, the black lead is threaded up through the foil side at Hole B and through the
component side hole marked (–) (see figure 1).
7. Carefully insert the 16 pin IC marked CD 4094 into the 16 pin socket, making sure
that the indentation or dimple on the IC matches the cutout on the socket.
8. Carefully insert the 8 pin IC marked NE555 into the 8 pin socket, making sure that
the indentation or dimple on the IC matches the cutout on the socket.
9. Visually check all solder connections for proper soldering technique, excess lead ends
trimmed, and no bridge connections.
10. Connect the 9 volt battery to the battery connector. Your Fun Light should now be
ready for functional testing.
Functional Test Procedure
1. With the component side facing up, grip the left edge of the PCB marked “PRESS
START” between your thumb and index finger, hold for about a ½ second, and let go.
This should cause LED L1 to light. An internal clocking pulse from the 555 timer will
then cause other LEDs to light sequentially (chase), one at a time, and then stop.
2. Hold “PRESS START” until L1 and L2 are lit and then release. The two lights will
chase simultaneously from left to right. The same test can be done for three or more
lights.
3. Hold “PRESS START” until all LEDs are lit and then release. The LED’s will turn off,
one at a time, from left to right.
4. Hold “PRESS START” for a moment, then release and then grip “PRESS START
again. A new pattern of lit LEDs with a space between them will chase from left to
right.
5. Press the “PRESS FASTER” edge of the board with your other fingers. The lights
should shift faster. Experiment by using one hand to start the pattern and the other to
control the chase speed of the pattern.
© 2014 Project Lead The Way, Inc.
Digital Electronics Project 1.1.8 Soldering Practice: Fun Light – Page 5
Project Completion
1. Once your Fun Light is functioning properly, attach one Velcro® strip to the battery and
the other to the foil side of the PCB. This will secure the battery to the PCB.
2. Remember to unplug the battery after using your Fun Light or the battery will die.
Conclusion
Answer the following questions related to the soldering/de-soldering process. You may use
this activity and the supporting presentation as a reference, but you will need other
references (textbooks, Internet, etc.) to answer all of the questions.
1. Solder is an alloy of what two metals?
2. What is tinning and why is it important to keep the tip of your soldering iron tinned?
3. List the six most common types of bad solder connections.
4. What are the two techniques that can be used to de-solder a component from a PCB?
5. The solder used in electronic application is frequently called 60/40 solder. Why?
6. What is a cold solder joint?
7. What is the melting point of 60/40 solder?
8. What is the typical wattage of a soldering iron used in electronic application?
© 2014 Project Lead The Way, Inc.
Digital Electronics Project 1.1.8 Soldering Practice: Fun Light – Page 6