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Thread: How to: Working with electronics

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    Ceann na Drochaide Bige! XcOM's Avatar
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    Default How to: Working with electronics

    Basic Electronics

    (Sources used listed at bottom)

    First off before you go any further you must remember some rules:

    1) NEVER work with electronics if you don’t feel competent to do so.
    2) Always make sure you follow basic safety instructions.
    3) ALWAYS disconnect all power before starting work.


    Above is a conceptual drawing of an atom. Atoms are the building blocks of matter. Everything is made of atoms, from rocks, to trees, to stars, to even yourself. An atom consists of a tightly packed nucleus containing one or more protons (colored red in the picture), and usually an equal number of neutrons (gray). Electrons (blue) surround the nucleus, forming an electron cloud. The number of electrons in an electrically stable atom is always equal to the number of protons in the nucleus.

    Soldering

    The most fundamental skill needed to assemble any electronic project is that of soldering. It takes some practice to make the perfect joint, but, like riding a bicycle, once learned is never forgotten! The idea is simple: to join electrical parts together to form an electrical connection, using a molten mixture of lead and tin (solder) with a soldering iron. A large range of soldering irons is available - which one is suitable for you depends on your budget and how serious your interest in electronics is.

    The use of lead in solder is now increasingly prohibited in many countries. "Lead free" solder is now statutory instead.

    Things to look for a soldering iron.

    Voltage: most irons run from the mains at 240V. However, low voltage types (e.g. 12V or 24V) generally form part of a "soldering station" and are designed to be used with a special controller made by the same manufacturer.

    Wattage: Typically, they may have a power rating of between 15-25 watts or so, which is fine 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. This also depends partly on the design of the "bit" (the tip of the iron). Consider a higher wattage iron simply as being more "unstoppable" when it comes to heavier-duty work, because it won't cool down so quickly.

    Temperature Control: the simplest and cheapest types don't have any form of temperature regulation. Simply plug them in and switch them on! Thermal regulation is "designed in" (by physics, not electronics!): they may be described as "thermally balanced" so that they have some degree of temperature "matching" but their output will otherwise not be controlled. Unregulated irons form an ideal general purpose iron for most users, and they generally cope well with printed circuit board soldering and general interwiring. Most of these "miniature" types of iron will be of little use when attempting to solder large joints (e.g. very large terminals or very thick wires) because the component being soldered will "sink" heat away from the tip of the iron, cooling it down too much. (This is where a higher wattage comes in useful.)

    A proper temperature-controlled iron will be quite a lot more expensive - retailing at say £40 (US$ 60) or more - and will have some form of built-in thermostatic control, to ensure that the temperature of the bit (the tip of the iron) is maintained at a fixed level (within limits). This is desirable especially during more frequent use, since it helps to ensure that the temperature does not "overshoot" in between times, and also guarantees that the output will be relatively stable. Some irons have a bimetallic strip thermostat built into the handle which gives an audible "click" in use: other types use all-electronic controllers, and some may be adjustable using a screwdriver.

    Yet more expensive still, soldering stations cost from £70 (US$ 115) upwards (the iron may be sold separately, so you can pick the type you prefer), and consist of a complete bench-top control unit into which a special low-voltage soldering iron is plugged. Some versions might have a built-in digital temperature readout, and will have a control knob to enable you to vary the setting. The temperature could be boosted for soldering larger joints, for example, or for using higher melting-point solders (e.g. silver solder). These are designed for the most discerning users, or for continuous production line/ professional use. The best stations have irons which are well balanced, with comfort-grip handles which remain cool all day. A thermocouple will be built into the tip or shaft, which monitors temperature.

    Anti-static protection: if you're interested in soldering a lot of static-sensitive parts (e.g. CMOS chips or MOSFET transistors), more advanced and expensive soldering iron stations use static-dissipative materials in their construction to ensure that static does not build up on the iron itself. You may see these listed as "ESD safe" (electrostatic discharge proof). The cheapest irons won't necessarily be ESD-safe but never the less will still probably perform perfectly well in most hobby or educational applications, if you take the usual anti-static precautions when handling the components. The tip would need to be well earthed (grounded) in these circumstances.

    Bits: it's useful to have a small selection of manufacturer's bits (soldering iron tips) available with different diameters or shapes, which can be changed depending on the type of work in hand. You'll probably find that you become accustomed to, and work best with, a particular shape of tip. Often, tips are iron-coated to preserve their life, or they may be bright-plated instead. Copper tips are seldom seen these days.

    Spare parts: it's nice to know that spare parts may be available, so if the element blows, you don't need to replace the entire iron. This is especially so with expensive irons. Check through some of the larger mail-order catalogues.

    ----------------------------------

    -----------------------------

    Copyright Notice
    Text © 1996-2006 Wimborne Publishing Limited, Wimborne, Dorset, England. Everyday Practical Electronics Magazine has provided this document as a free web resource to help constructors, trainees and students. You are welcome to download it, print it and distribute it for personal or educational use. It may not be used in any commercial publication, mirrored on any commercial site nor may it be appended to or amended, or used or distributed for any commercial reason, without the prior permission of the Publishers.

    Photographs © 1996-2006 Alan Winstanley WORLD COPYRIGHT RESERVED

    Every care has been taken to ensure that the information and guidance given is accurate and reliable, but since conditions of use are beyond our control no legal liability or consequential claims will be accepted for any errors herein.

    The British mains voltage supply is 230V a.c. and you should amend ratings for local conditions.

    Please check the Everyday Practical Electronics Web Site for details of the current issue, subscription rates, Back issue availability and contact information.
    Last edited by Crimson Sky; 02-28-2007 at 11:56 AM.


    Mary had a little lamb. It bumped into a pylon. Ten thousand volts went up its arse and turned its wool to nylon!

  2. #2
    Ceann na Drochaide Bige! XcOM's Avatar
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    Default Re: How to: Working with electronics

    Turning to the actual techniques of soldering, firstly it's best to secure the work somehow so that it doesn't move during soldering and affect your accuracy. In the case of a printed circuit board, various holding frames are fairly popular especially with densely populated boards: the idea is to insert all the parts on one side ("stuffing the board"), hold them in place with a special foam pad to prevent them falling out, turn the board over and then snip off the wires with cutters before making the joints. The frame saves an awful lot of turning the board over and over, especially with large boards. Other parts could be held firm in a modeller's small vice, for example.

    Solder joints may need to possess some degree of mechanical strength in some cases, especially with wires soldered to, say, potentiometer or switch tags, and this means that the wire should be looped through the tag and secured before solder is applied. The down side is that it is more difficult to de-solder the joint (see later) and remove the wire afterwards, if required. Otherwise, in the case of an ordinary circuit board, components' wires are bent to fit through the board, inserted flush against the board's surface, splayed outwards a little so that the part grips the board, and then soldered.

    In my view - opinions vary - it's generally better to snip the surplus wires leads off first, to make the joint more accessible and avoid applying a mechanical shock to the p.c.b. joint. However, in the case of semiconductors, I often tend to leave the snipping until after the joint has been made, since the excess wire will help to sink away some of the heat from the semiconductor junction. Integrated circuits can either be soldered directly into place if you are confident enough, or better, use a dual-in-line socket to prevent heat damage. The chip can then be swapped out if needed.

    Parts which become hot in operation (e.g. some resistors), are raised above the board slightly to allow air to circulate. Some components, especially large electrolytic capacitors, may require a mounting clip to be screwed down to the board first, otherwise the part may eventually break off due to vibration.

    The perfectly soldered joint will be nice and shiny looking, and will prove reliable in service. I would say that:

    * cleanliness
    * temperature
    * time
    * adequate solder coverage

    are the key factors affecting the quality of the joint. A little effort spent now in soldering the perfect joint may save you - or somebody else - a considerable amount of time in troubleshooting a defective joint in the future. The basic principles are as follows.

    ---------------------------
    Really Clean

    Firstly, and without exception, all parts - including the iron tip itself - must be clean and free from contamination. Solder just will not "take" to dirty parts! Old components or copper board can be notoriously difficult to solder, because of the layer of oxidation which builds up on the surface of the leads. This repels the molten solder and this will soon be evident because the solder will "bead" into globules, going everywhere except where you need it. Dirt is the enemy of a good quality soldered joint!

    Hence, it is an absolute necessity to ensure that parts are free from grease, oxidation and other contamination. In the case of old resistors or capacitors, for example, where the leads have started to oxidise, use a small hand-held file or perhaps scrape a knife blade or rub a fine emery cloth over them to reveal fresh metal underneath. Stripboard and copper printed circuit board will generally oxidise after a few months, especially if it has been fingerprinted, and the copper strips can be cleaned using an abrasive rubber block, like an aggressive eraser, to reveal fresh shiny copper underneath.

    Also available is a fibre-glass filament brush, which is used propelling-pencil-like to remove any surface contamination. These tend to produce tiny particles which are highly irritating to skin, so avoid accidental contact with any debris. Afterwards, a wipe with a rag soaked in cleaning solvent will remove most grease marks and fingerprints. After preparing the surfaces, avoid touching the parts afterwards if at all possible.

    Another side effect of having dirty surfaces is the tendency for people to want to apply more heat in an attempt to "force the solder to take". This will often do more harm than good because it may not be possible to burn off any contaminants anyway, and the component may be overheated. In the case of semiconductors, temperature is quite critical and they may be harmed by applying such excessive heat.

    Before using the iron to make a joint, it should be "tinned" (coated with solder) by applying a few millimetres of solder, then wiped on a damp sponge preparing it for use: you should always do this immediately with a new bit, anyway. Personally, I always re-apply a very small amount of solder again, mainly to improve the thermal contact between the iron and the joint, so that the solder will flow more quickly and easily. It's sometimes better to tin larger parts as well before making the joint itself, but it isn't generally necessary with p.c.b. work. (All EPE printed circuit boards are "roller-tinned" to preserve their quality and to help with soldering.) A worthwhile product is Weller's Tip Tinner & Cleaner, a small 15 gram tinlet of paste onto which you dab a hot iron - the product cleans and tins the iron ready for use. An equivalent is Adcola Tip-Save.

    Normal electronics grade solder is now "lead free" and typically contains Sn 97 Ag 2.5 Cu 0.5 (i.e. 97% tin, 2.5% silver and 0.5% copper). It already contains cores of "flux" which helps the molten solder to flow more easily over the joint. Flux removes oxides which arise during heating, and is seen as a brown fluid bubbling away on the joint. The use of separate acid flux paste (e.g. as used by plumbers) should NEVER be necessary in normal electronics applications because electronics-grade solder already contains the correct grade of flux! Other solders are available for specialist work, including aluminium and silver-solder. Different solder diameters are produced, too; 20-22 SWG (19-21 AWG) is 0.91-0.71mm diameter and is fine for most work. Choose 18 SWG (16 AWG) for larger joints requiring more solder.

    Temperature

    Another step to successful soldering is to ensure that the temperature of all the parts is raised to roughly the same level before applying solder. Imagine, for instance, trying to solder a resistor into place on a printed circuit board: it's far better to heat both the copper p.c.b. and the resistor lead at the same time before applying solder, so that the solder will flow much more readily over the joint. Heating one part but not the other is far less satisfactory joint, so strive to ensure that the iron is in contact with all the components first, before touching the solder to it. The melting point of most solder is in the region of 188°C (370°F) and the iron tip temperature is typically 330-350°C (626°-662°F). The latest lead-free solders typically require a higher temperature.

    Now is the time

    Next, the joint should be heated with the bit for just the right amount of time - during which a short length of solder is applied to the joint. Do not use the iron to carry molten solder over to the joint! Excessive time will damage the component and perhaps the circuit board copper foil too! Heat the joint with the tip of the iron, then continue heating whilst applying solder, then remove the iron and allow the joint to cool. This should take only a few seconds, with experience. The heating period depends on the temperature of your iron and size of the joint - and larger parts need more heat than smaller ones - but some parts (semiconductor diodes, transistors and i.c.s), are sensitive to heat and should not be heated for more than a few seconds. Novices sometimes buy a small clip-on heat-shunt, which resembles a pair of aluminium tweezers. In the case of, say, a transistor, the shunt is attached to one of the leads near to the transistor's body. Any excess heat then diverts up the heat shunt instead of into the transistor junction, thereby saving the device from over-heating. Beginners find them reassuring until they've gained more experience.

    Solder Coverage

    The final key to a successful solder joint is to apply an appropriate amount of solder. Too much solder is an unnecessary waste and may cause short circuits with adjacent joints. Too little and it may not support the component properly, or may not fully form a working joint. How much to apply, only really comes with practice. A few millimetres only, is enough for an "average" p.c.b. joint, (if there is such a thing).


    Copyright Notice
    Text © 1996-2006 Wimborne Publishing Limited, Wimborne, Dorset, England. Everyday Practical Electronics Magazine has provided this document as a free web resource to help constructors, trainees and students. You are welcome to download it, print it and distribute it for personal or educational use. It may not be used in any commercial publication, mirrored on any commercial site nor may it be appended to or amended, or used or distributed for any commercial reason, without the prior permission of the Publishers.

    Photographs © 1996-2006 Alan Winstanley WORLD COPYRIGHT RESERVED

    Every care has been taken to ensure that the information and guidance given is accurate and reliable, but since conditions of use are beyond our control no legal liability or consequential claims will be accepted for any errors herein.

    Please check the Everyday Practical Electronics Web Site for details of the current issue, subscription rates, Back issue availability and contact information.
    Last edited by Crimson Sky; 02-28-2007 at 11:59 AM.


    Mary had a little lamb. It bumped into a pylon. Ten thousand volts went up its arse and turned its wool to nylon!

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    Paradox Sausage DaveW's Avatar
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    Default Re: How to: Working with electronics

    Great guide! I'm sure this will help a lot of people. Maybe instead of having these in the forums, we could make a part of the site dedicated to how-to's? Any thoughts on this idea?

    What's with the atom tho?

    -Dave
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    Ideas are just knowledge soaked in alcohol.
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    Did I just get in a Volvo? Volvo's don't have guns!

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    ATX Mental Case jsb666's Avatar
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    Default Re: How to: Working with electronics

    XcOM great guide! this will help me a lot i know a little bit about soldering but that has filled in all the blanks i had before. Im about to attach 2 switches to my dvd-rom's tomorrow and this will help me do that with more confidence. Thanks

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    Ceann na Drochaide Bige! XcOM's Avatar
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    Default Re: How to: Working with electronics

    you welcome all, and i put the atom thing in as a basic guide, i thought i would give a bit of insite into how it works.

    Took me about 3Hours to write it. and if you want to start a proper section on How To's/Guides i am more than willing to help.


    Mary had a little lamb. It bumped into a pylon. Ten thousand volts went up its arse and turned its wool to nylon!

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    Woodworking unicycling bodybuilder tybrenis's Avatar
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    Default Re: How to: Working with electronics

    Awesome guide XcOM! May I publish it on my site (all credits will of course be given)? I would love to put it on my site where many would see it, I am starting a collection of the guides here to put on my site. That way, everyone can access them all quickly and conveniantly.
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    Jon has altered his cock to compensate.

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    Average Rocket Scientist Aero's Avatar
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    Default Re: How to: Working with electronics

    nice guide Xcom. May I suggest you add a small section about soldering wire to wire, and using heatshrink tubeing? It seems that wire to wire is one ofthe hardest thing to keep from spliting so naturally it should have a welcome spot in your guide.

    Thanks for the great guide XcOM, i'm sure it will help many rookies to realize their electonic visions.

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    some custom title eh Cannibal23's Avatar
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    Default Re: How to: Working with electronics

    ************ Lead free solder information *******************

    the company i work for does alot of international jobs and we have had some requrements for lead free solder. One little known thing about solder that is very rich in tin however is that over time (long time) it can cause little finger like formations on the surface of the solder. although these things are apparently very small they could cause shorts in electronic componants that are packed very closely togeather. here is a link to a very technical document regarding the above items for those of you who are intersted

    http://doc.tms.org/ezMerchant/prodtm...df?OpenElement

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    Ceann na Drochaide Bige! XcOM's Avatar
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    Default Re: How to: Working with electronics

    Quote Originally Posted by tybrenis
    Awesome guide XcOM! May I publish it on my site (all credits will of course be given)? I would love to put it on my site where many would see it, I am starting a collection of the guides here to put on my site. That way, everyone can access them all quickly and conveniantly.

    yea sure, give credit and you can,

    P.S can you send a link to me for the website


    Mary had a little lamb. It bumped into a pylon. Ten thousand volts went up its arse and turned its wool to nylon!

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    Woodworking unicycling bodybuilder tybrenis's Avatar
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    Default Re: How to: Working with electronics

    Quote Originally Posted by XcOM
    yea sure, give credit and you can,

    P.S can you send a link to me for the website
    Thanks! I am gathering all the guides here and editing, revising, and then publishing them for my site so they can all be accessed easily. Looks like your guide won't need any editing, it was very well written :p .

    My site is www.powerpackedpc.com.
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