Saturday, 19 May 2012

BEGINNERS GUIDE

BEGINNERS GUIDE

Want to make your 1st project lets start.

BASIC TOOLS

Before starting your new project you will require a few basic tools to complete your first project. The most important tool you will require is soldering iron and some solder wire. You will also need some more tools like wire-cutters, wire-strippers and a pair of small pliers. Other items are also useful although not essential.
ESSENTIAL TOOLS REQUIRED ARE AS FOLLOWS-
Soldering iron – soldering iron is a hand tool used for soldering the components. It supplies heat to melt the solder so that it can flow into the joint between two workpieces. You can use power rating of between 15-25 watts which is suitable for most work. A higher wattage does not mean that the iron runs hotter - it simply means that there is more power in reserve for coping with larger joints.  
Bit size – WE should pick a tip that's slightly smaller than the pad you're soldering. As bit size vary in shape size and according to the types of work. Pyramid tips with a triangular flat face and chisel tips with a wide flat face are useful for soldering sheet metal, Fine conical or tapered chisel tips are typically used for electronics work. If you are a beginner we suggest you to use Spade shape bit.
Solder wire  It is a fusible metal alloy used to join metal work pieces together and having a melting point below that of the work piece. Solder is a metal or metallic alloy. The most common used alloy is some combination of tin and lead. The most common alloys used for electronics work are 60/40.Melting points of some common solder alloys.

Tin/Lead   Melting Point
40/60 230 degrees C          
50/50 214 degrees C
60/40 190 degrees C
63/37 183 degrees C
95/5               224 degrees C

If you need to solder very fine electrical circuits, like jewelry or joints that are hidden in very tight places you should use the solder wire in the range from .01-inch to .05-inch, and if you want to solder household electrical work you should go for .5-inch.

For beginner we will suggest they should go for 20 -22 SWG (standard wire gauge) of thickness.

Flux Flux act as a cleaning, flowing, purifying agent. As a cleaning agent, fluxes facilitate soldering, brazing,
and welding by removing oxidation from metal to be joined. Commonly used fluxes are: ammonium chloride for soldering tin, hydrochloric acid and zinc chloride for iron and braze for welding ferrous metal.

Cutting pliers Side cutters have blades placed at one side so that they  can be used to easily and neatly crop the ends of component leads after the components have been soldered to a piece of  Printed Circuit Board (PCB).

Long nose pliers A pair of long nose pliers is used for holding or bending the leads of components and holding nuts while you tighten bolts.
Wire strippers For soldering we will most likely be use thin wire like single core or multi strain wire when connecting off-board components to the strip board or PCB, or when constructing a prototype circuit on breadboard. Wire strippers like the one shown can be easily adjusted to make stripping the insulation off these types of wire simple.
Track cutter A 3mm drill bit can be used instead, in fact the tool is usually just a 3mm drill bit with a proper handle fitted.
Tweezers Tweezer is a very useful tool for holding screws and  aligning them into their threaded holes and for holding thin wires while soldering or picking up and holding small components.
Magnifying glass Magnifiers are used to see the small markings on components and also for examining circuit board traces and solder connections. If you can, you should solder under magnification using a magnifying work lamp, but you can start with a hand magnifier.



De-Solder tool Useful when you need to remove a solder joint for whatever reason you will require the following tools-
De-solder pump It is a tool for removing solder when de-soldering a joint to correct a mistake or replace a component. It is a spring-loaded suction pump with Teflon nozzle.

De-soldering wick It is a copper braid woven using fine copper wire and is impregnated with flux. It comes in rolls of one to one-and-a-half meter length. About a cm or so of the wick is placed over the soldered joint to be de-soldered and the hot solder-iron tip is pressed over it. As the solder melts, it gets trapped in to the braid’s mesh.
TEST EQUIPMENT
Multimeter This is the basic equipment you should have with you because if your circuit does not work you can troubleshoot it with the help of multimeter. Multimeters come in two flavors:
1.Digital
2.Analog - Analog multimeters are old Fashioned — but still useful
Multi meters come with a pair of test leads. Generally Black for the ground connection, Red for the positive connection.
You can use a multi meter to take a variety of electrical measurements. With this one test equipment you can -
  • Measure AC voltages
  • Measure DC voltages
  • Measure resistance
  • Measure current going through a circuit
  • Measure continuity (whether a circuit is broken or not)
  • Test the operation of diodes and transistors  
My recommendation:  Have you own multi meter
Power Supply  Is also very useful for powering circuits that you are testing. One with a variable voltage up to at least 20V is best. The current rating doesn't need to be that high; 1A maximum is fine for most jobs.

MOUNTING OF COMPONENTS
Insert the components  Try to insert components in order of size, smallest first. It can be very difficult to insert small components if larger ones are in the way. If any wire links have to be solder then solder it first. Following order may be follow for soldering the components
1. Jumpers (wire connection)
2. Resistor
3. IC base
4. Capacitor
5. Inductors
6. Transistor
7. LED
8. Triac
9. Voltage regulators
10. Transformer
Make sure Components such as resistors sit flat on the board, so there is no gap between the component and the board. The only exception is where components may dissipate some heat. Apart from looking neater, it gives the components some protection. However, some components such as transistors should stand slightly proud of the board.
Be systematic About inserting components, and try to make the board look as neat as possible. A neat looking board is more likely to work first time too. If you are not happy with how a component has gone in, or a joint looks bad, carefully remove it and try again. Solder joints should be shiny, if not you have probably made a 'dry joint' which needs removing and re-making.
Check  You have connected external components the right way round, and to the right points on the board. Components such as LEDs, diodes, transistors etc. are polarity sensitive.

DOUBLE-CHECK THE POLARITY OF THE BATTERY AND ANY POLARISED COMPONENTS (CAPACITORS, TRANSISTORS ETC.) AS A MISTAKE HERE COULD DAMAGE THE CIRCUIT!

Some components require special care when soldering. Many must be placed the correct way round and a few are easily damaged by the heat from soldering. Appropriate warnings are given in the table below, together with other advice which may be useful when soldering.
 
Components
Pictures
Reminders and Warnings
1
IC Holders
(DIL sockets)
*Connect the correct way round by making sure the notch is at the correct end. 
Do NOT put the ICs (chips) in it while soldering.
2
Resistors*No special precautions are needed with resistors.
3
Small value capacitors
(usually less than 1µF)
*These may be connected either way round. 
Take care with polystyrene capacitors because they are easily damaged by heat
.
4
Electrolytic capacitors
(1µF and greater)
*Connect the correct way round. They will be marked with a + or - near one lead.
5
Diodes*Connect the correct way round silver line is for cathode. 
Take care with germanium diodes (e.g. OA91) because they are easily damaged by heat.
6
LEDs*Connect the correct way round. 
The diagram may be labelled 
a or + for anode and k or - for cathode. The cathode is the short lead and there may be a slight flat on the body of round LEDs.
7
Transistors*Connect the correct way round. 
Transistors have 3 'legs' (leads) so extra care is needed to ensure the connections are correct. 
Easily damaged by heat.
8
Wire Links *
single core wire
Use single core wire on breadboard; this is one solid wire which is plastic-coated. 
If there is no danger of touching other parts you can use tinned copper wire, this has no plastic coating and looks just like solder but it is stiffer.
9
 Buzzers  Connect the correct way round.
10Wires Multi Strain*
You should use stranded wire which is flexible and plastic-coated while soldering wires on PCB 
Do not use single core wire because this will break when it is repeatedly flexed.





SOLDERING

So, now you've got some tools, and you're ready to start. This will give you something to practice soldering with. When you've got all now it's time to get started.

HOW TO SOLDER

Plug in the iron And wait about 5 minutes for it to heat up. Place it on something that won't burn, and make sure the 'bit' isn't touching anything, including the mains lead. Ideally use a stand.
Tin the bit Melt a small amount of solder onto the tip and wipe the hot iron on a wet sponge use cellulose sponge, not a synthetic one that will melt and stick to the iron. Make sure the sponge is damp - using it dry will only mess up the sponge and won't clean the tip. This will put a layer of solder on the tip.
Bend the leads Bend the component with pliers to fit the board. Insert it into the board from the side without metal strips and bend the leads outwards on the other side to hold it in.
Benefits of Pre-Bending
  • Pre-bending is a technique that allows components to be easily inserted into a PCB.
  • Pre-bending also allows components to lay more flush with the board.
Bending components to the correct bend radius takes practice, but mastering the technique will reap rewarding benefits.


Place the tip Of the iron on the lead where it comes through the board on the side with the metal strips. Make sure it touches the lead and the board.

Wait a second Or two for the board and the lead to heat up. Don't leave it too long; otherwise you will damage the component. This is particularly important with semiconductors - transistors, diodes, I.C.'s etc.
Feed the solder Into the joint until it forms a ring around the leads of the component. It should stick properly to both the lead and the copper strip on the board. DO NOT carry the solder to joint on the tip of the iron, this almost invariably produces a bad joint.


Remove the iron  And allow the joint to cool naturally. DO NOT cool it by blowing on it. The joint should look volcano shaped. If it is not shiny, or has formed into a blob then you have made a 'dry' joint. If the joint is not complete re-apply the iron and add a bit more solder.


If you need to remove the solder Use a de-soldering tool or solder braid, or melt the solder and tap the edge of the board on the worktop to knock it off. Try again - practice makes perfect!
When the joint is OK Use side cutters to cut the component lead. Repeat the process for the other leg(s) of the component.
When you've finished Soldering, clean the tip on the damp sponge and then re-tin it with fresh solder before you unplug the iron. This protects the tin plating on the tip and prevents it.
Rules for good soldering-
Rule #1: A good mechanical connection is necessary before you solder!
Rule #2: Strike while the iron is hot!
Rule #3: Heat the work, not the solder! 
Rule #4: Inspect the connection under magnification! 

COMMON PROBLEMS

Too much solder  Joint will form into a blob, solder may bridge between strips on the board. Remove ALL the solder as described above and try again.
Too little solder  Joint not complete, physically weak, possible not electrically sound either. Re-apply the iron and add a bit more solder.
Solder will not stick  Component lead or board may be greasy or tarnished. Generally you should clean the lead and the board before soldering them.
Now start building our project and make sure you can produce good solder joints, as you will only spend more time later de-soldering bad joints, and may damage the components. When you're happy that you’re soldering is good, it's time to start more projects.

TESTING & TROUBLESHOOTING

Before you apply power, read the instructions carefully to check you haven't missed anything. Check again that you have polarity sensitive components that you have put them in right way around, and that all components are in the correct places. Check the underside of the board carefully for short circuits between tracks - a common reason for circuits failing to work.
When you are sure everything is correct, apply power and see if the circuit behaves as expected, again following the instructions given in manual.
If it works, WELL DONE! You have your first working circuit - be proud of it!
If it doesn't quite work as expected, or doesn't work at all, don't despair. The chances are the fault is quite simple. However, disconnect the power before reading on.
Check the basic's first  Is power supply is coming ? Are you sure the 'On' switch really is on? (Don't laugh, it is the common mistake) If the project has other switches and controls check these are set correctly.
Next  Check again all the components are in the correct place - refer to the diagram in the instructions. Look again at the underside of the board - are there any short circuits? These can be caused by almost invisible 'whiskers' of solder, so check for these with a magnifying glass in good light.
Pull the components gently  To see if they are all fixed into the board properly. Check the soldered joints - poor soldering is the most common cause of circuits failing to work. The joints should by shiny, and those on the circuit board should be volcano shaped with the component wire end sticking out of the top. If any look suspect then redo them. Remove the solder with a solder sucker or braid and try again.
Check For solder splashes shorting across adjacent tracks on the circuit board, especially where connections are very close such as on integrated circuits ('chips'). Solder splashes are most likely on pcb. You can check for shorts using a multimeter set it to continuity range, or low resistance range. Be aware if you do this though, that there will be a resistance between some tracks due to the components. Any resistance below 1 ohm between tracks is likely to be a solder splash. Run the soldering iron between tracks on pcb to remove any solder bridges.
If the circuit Still fails to work you will need to refer to the circuit diagram and take voltage readings from the circuit to find out what's wrong. You will need a multimeter to do this. Remember that if you find one fault such as a reversed component and correct it, it might have caused damage to other components.
Now you could build more kits to get more confidence.

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