Before assembling this torch make sure you have checked out the breadboard switch circuit so that you have an understanding of how the circuit works.
Equipment / Materials:
- Safety Glasses
- Solder (0.5 to 0.8mm leaded is recomended)
- Dry scourer or wet sponge for cleaning solder tip
- Soldering iron (adjusted to about 285 – 300 degrees)
- Side cutters
- Long nosed pliers
- Component bending tool
- Multimeter (for diagnosing problems)
- Soldering mat (to protect bench)
- Air fume extractor (or room with good air flow)
- Ensure safety glasses are worn whilst cutting component leads and soldering
- Work under fume extraction system to reduce inhalation of bad air
- Do not touch tip of soldering iron or any component that has recently been soldered
- Wash hands with soap after soldering to remove fluxes and lead.
|PCB||1||LED Torch PCB|
|R1||1||15 Ohm Resistor|
|LED1||1||White LED 5mm|
|S1||1||Push Button Switch|
|Bat||1||CR2450 Coin Battery|
|J1||1||CR2450 Battery Clip|
1. Please check safety list before beginning above before proceeding.
Identify / collect the following tools and set up work space: component bending tool, side cutters, long nose pliers.
2. Identify the following parts; 15 Ohm resistor, push button switch, 5mm white LED, CR2450 3V Cell battery, CR2450 battery clip and LED Torch PCB.
3. Using the component bending tool on the second smallest step, bend both sides of the 15 Ohm (Brown, Green, Black, Gold) resistor to 90 degrees.
5. Using long nose pliers bend both leads of the resistor out to 45 degrees. You need the bend of the resistor to be sharp and close to the PCB. This process is called semi clinching.
6. Using the side cutters with the flat side facing the PCB and at 45 degree angle to the surface. Place the point sharp point of the blades either side of the resitor leg resting on the outside edge of the solder pad. This will automatically determine the length of the lead.
7. Before soldering you will need to prepare the tip of the soldering iron. Notice in the photo bellow the tip is a dull grey colour. Tinning the tip of the soldering iron cleans the surface of the tip and allows it to conduct heat into the pad faster.
8. Melt some solder onto the tip of the Iron and then using either a dry scourer style or wet sponge style cleaner wipe the solder off of the tip.
10. Watch the video demonstration of the first resistor joint. Notice the soldering iron tip is used to heat up the solder pad for about 1-2 seconds before the solder is introduced. A small amount of solder is fed into the joint and then the solder wire is removed before removing soldering iron to allow joint to solidify.
11. Hold the LED in the long nose pliers so that the flat spots on the legs are just above the edge of the pliers jaws.
13. Insert the LED into the holes labelled LED1. ENSURE YOU HAVE THE LONGER LEG ON POSITIVE SIDE. There is also a flat surface on the side of the LED that should line up with the white silk screen if the LED were standing upright.
14. Semi clench the LED legs using the same method as the resistor. Solder on leg of the LED then check it is still aligned correctly and leads are flat along the top of the PCB.
15. Insert push button switch. You do not have to bend the legs as they should spring out and hold them self.
16. Solder one joint of push button switch, check the switch is sitting flat on the PCB before soldering remaining three joints.
17. Sometimes the battery does not make good contact with the square solder pad that sits under the battery clip. It is recommended that you put a very thin layer of solder on the pad seen in the video below.
18. Finally insert the battery clip on the top side of the PCB.
19. It would be helpful to work in partners so that the PCB can be held upside down on the table so the battery clip is fully inserted. Solder one of the joint of the battery clip. THE WHOLE CLIP WILL GET A LITTLE BIT HOT AS IT IS CONDUCTIVE. Ensure the clip is fully inserted with no gap between PCB and sides of clip before soldering second joint.
20. Check that all joints are neat and have enough solder so that it flowed out the the edge of the pad but does not bubble up away from the PCB.