Electronics Workshop Manual
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Contents |
[edit] Introduction
The Electronics Workshop Manual is at the moment a rough collection of ideas. It will hopefully be refined over time into a coherent whole.
It is intended to give practical assistance in constructing and designing electronic circuits, helping with.
[edit] Selecting components
[edit] Basics
Selection of components is a complex matter. There are millions of different sorts of components, available through thousands of different sources.
[edit] Procurement of components
Firstly, you need to select your component, and obtain a full datasheet. Then you need to obtain one or more for prototyping. If the prototype is not the only device to be made, then you need to find out how to source these for production.
You should do this before ordering anything, or in many cases, before doing detailed design, if using non commodity parts.
Designing a product for sale of 50 units, making a prototype, and then finding that a key component is only available in reels of 5000, and there is a 6 month lead-time should be avoided at all costs!
Samples are free or reduced cost components supplied directly by manufacturers or through distributors.
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- Distributors
These vary in scope from digikey, mouser and farnell, which stock many tens of thousands of items, and will deliver to anyone, with small minimum order fees. To [1], which is a narrowly focused enthusiast site catering to the hobby market, with hundreds of lines.
Many components are "in stock" (on the shelf) at distributors like the above, in single items. Be aware that those distributors also list many, many things in their catalog that are not "in stock" -- after you order a "not in stock" part, it may be months before you get one in your hand. Some parts are even more difficult to procure. For example, special components that are targeted at mobile phones, ADSL routers, or other specialised fields may be difficult or impossible to source in volumes less than "1 reel" (which may be thousands of parts).
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- Directly from the manufacturer
An increasing number of manufacturers have begun to offer online purchase of components, for small order quantities. for example Maxim and freescale. These may have on occasion much longer lead-times (months) than distributors who hold stock.
[edit] Skills
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- Soldering
- Through hole
- SMD
- Reflow
- Hot air
- PCB manufacture
- When to buy
- Toner Transfer
- Photographic methods
- Soldering
[edit] Component manufacture
[edit] When not to.
Generally, there is absolutely no reason to attempt to manufacture your own components. Attempting to will often simply result in a poorly performing larger, more costly, less stable component. There are exceptions.
- The component is unobtainable.
- You don't care much about the value, or can adjust other aspects of the circuit, or you can easily measure and adjust it till it's the right value.
- Obtaining specially made components can be very expensive for some items.
[edit] Inductors/transformers
- Air-cored inductors for HF or high power usage can be a few turns of wire or pipe, these often take moments only to construct, and may be hard to source.
- Transformers of all but the most common sorts may be hard to source, for small quantities, there are kits to make mains transformers readily available. This allows you to make a transformer with several output windings, isolated as you wish.
- SMPS transformers. Many switched-mode power supplies use a specially designed transformer. This also lets the designer vary the number of turns and arrangement, to optimise the design.
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- picofarad capacitors
- Low value resistors
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It will not cover electronics theory in general, though 'rules of thumb' for circuit design may be included.
[edit] Further reading
- The book Basic Electrical Generation and Distribution#Switched Mode Power Supply has more details on SMPS.
- Practical Electronics
