1.1.8.A Solder & De-Solder Practice

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 ten-year-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

· 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

Parts List – Fun Light

Qty

Item

Symbol (on PCB)

Pictorial Diagram

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

Watch polarity

Anode = (+) = long lead

Cathode = ( - ) = short lead

L1 – L8

1

IC Socket (16 pin)

U1

Watch for orientation of cutout – match to illustration on PCB.

1

IC CD-4094 (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.

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.

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.

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 1