The Art of Engineering

I visited the Natural & Organic Expo last weekend and learned a few things.

1. Polystyrene can be and is being recycled in Cape Town.
   

   From the reading that I have done I thought that polystyrene was expensive and inefficient to recycle, mainly due to the problems associated with transporting such a light plastic, but polystyrene is actually collected, melted into ingots and recycled into picture frames, stationery, cornices, skirting boards, hangers and seedling trays. In Cape Town EPS Reclaim in Montague Gardens collects and smelts polystyrene. Find your nearest polystyrene drop off point.

2. There is clearly a big demand for natural cleaning products.
   

   I was amazed at how many different natural, organic and bio–degradable household cleaning products were on show. The demand and acceptance of these products is growing not just for environmental reasons, but also due to health concerns such as allergic reactions.

3. Oxi-degradable plastics are creating headaches for recyclers.
   

   I have written about oxi–degradable plastics before. It is important to realise that oxi–degradable plastic is very different from bio–degradable plastic. Companies like Green Home make bio–degradable plastic from plant sources (in their case bagasse, a byproduct of the sugar industry), while oxi–degradable plastics are normal plastic (like polyethylene) with the addition of a metal salt which causes them to break down over time. In South Africa oxi–degradable plastics have been used mainly for fruit and bread bags. The problem with these types of plastics is that they are indistinguishable from normal plastics and it is difficult to know how far the degradation process has progressed. Oxi–degradable bags pollute the recycling stream and result in a poor quality end product.


4. Bio–degradable plastics require education and infrastructure.
   

   Bio–degradable plastic products made from sustainable sources (such as bagasse, mentioned above) may provide a viable alternative to plastic in some cases. It is important that they are manufactured from sources other than food crops (plastic from corn is unsustainable). A problem that needs to be addressed (and is being addressed by manufacturers such as Green Home) is how to manage the waste from these products. Simply dumping bio–degradable plastic into a landfill is undesirable. Bio–degradable plastics will not degrade in a landfill, which means effective collection and composting needs to take place. Consumers can compost these packages at home, but without education it is unlikely that this will happen. Education, collection and composting infrastructure is an important aspect of bio–degradable plastic.

5. Egg yolks contain colourant.
   

   Pick 'n Pay is selling a new range of indigenous free range eggs, and one of the marketing points is "No yolk colourants." Yolk colourants? It turns out that chicken feed is often supplemented to increase its carotenoid content to obtain a more consistent colour yolk. The supplements used appear to be natural or "nature identical" such as lutein and canthaxanthin.

It was good to meet new people, get exposed to a few new ideas and to find new sources of organic and environmentally aware products. If you are in Cape Town and the surrounding area then make a point to go next year.

This post is aimed at electronic engineers working with electronic design automation (EDA) packages.

As an electronic engineer you have probably been through it. It all starts simply and clearly. You need to draw a schematic; so you make some symbols, attach some attributes to them and get going. Then you draw some footprints for the PCB layout and make sure the correct footprint names are attached to the components you have created. The boards go the PCB manufacturer and you use a simple spreadsheet to manage the bill of materials (BOM). Everything goes nice and smoothly – you are happy.

Then another project comes along – a bigger one with more engineers working on it. You carry on like you have before, explaining to people how to create new components and footprints and how to make sure the part numbers are correct. It all seems to be going well. The PCBs and components arrive, but something is not quite right. One of the components (an expensive one!) is the wrong part, and another component does not fit onto the PCB footprint correctly (even though there is another component with the same footprint that does fit correctly). What went wrong?

Eventually with more projects and more people managing the component library becomes a full time job for someone, and getting a new component approved is a lengthy process for engineers. Let's not even talk about managing the now massive stock and BOM spreadsheet which keeps you awake at night. The quick process you started with has become a slow moving, time consuming beast. We need to find a way to kill that beast so that engineers can spend more time creating solutions to problems, and less time on administration.

There are two ways to handles components. We can either have "heavy" symbols, or "light" symbols. First a few definitions so that we are all talking the same language.

component	:	an actual physical part.
symbol	:	a diagram depicting a component which is placed in a schematic drawing.
footprint	:	the physical layout of a component on a PCB.

A heavy symbol has all of its attributes, such as part name, value, voltage, tolerance, footprint, ordering number, etc. specified in the symbol library. A light symbol has no attributes specified in the library and all attributes are added at a schematic level.

There are some obvious flaws with each approach. A heavy symbol library will quickly grow in size – just think about having a symbol defined for each different opamp or resistor that is used. The graphical representation of an opamp is generic to a number of different parts, but now duplicates are created for each component. If a fault does creep into the library it can result in a number of different symbols needing to be fixed.

With a light symbol library all the attributes are added to the schematic. Maintaining the symbols is easy (because there are fewer), but ensuring that the correct attribute information is added can lead to errors (each time data is manually copied or entered there is the potential for an error).

There are also some obvious advantages. A heavy symbol immediately makes a lot of information available in the schematic which can be passed on to other tools, such as the footprint to the PCB layout package, or the part number to the BOM. A light symbol allows for information to be drawn from multiple sources, and the schematic can be updated without having to propagate the changes back into the library.

Here is a brief summary of the feature of each type of symbol.

Heavy symbols:

• Data duplication,
• Errors requires changes to numerous symbols,
  
• Require a librarian to maintain symbol library sanity,
• Single source of information.

Light symbols:

• No data duplication,
• Errors can be fixed at schematic level, or only affect a single symbol,
• Allows multiple data sources for component information,
• Requires addition of attributes at schematic level.

If you remember that I am against information duplication, then you should have guessed that I am in favour of light symbols.

The "light" and "heavy" nomenclature arose out of discussions on the gEDA mailing list. The gEDA wiki has a brief summary, and the two threads which I think are the most relevant are "Light vs. Heavy gschem symbols?" and "Heavy symbols and such."

Nature strives towards efficiency. Efficiency can be defined as any waste which occurs in achieving a goal, or, "The ratio of the effective or useful output to the total input in any system."

Efficiency is the perfect use of material. Packaging is inefficient, as the "goal" is what is inside the package, while the packaging becomes waste. Packaging can be efficient if it is reused, as it never exits the system. Recycling requires extra energy, and is therefore less efficient than reusing, but more efficient than throwing away packaging. Using less to achieve the same is material efficiency. Smaller products, less packaging, lower material consumption. Have you ever considered how you could design exactly the same thing but smaller? Electronic engineers, think about small 0402 or 0201 size resistors over larger ones – in most cases they are functionally equivalent, but use less material and require less space on a PCB.

Efficiency is the perfect use of fuel. Internal combustion engines are around 20% efficient – that means 80% of the energy you put into your car is wasted. If cars were 100% efficient they would have zero emmissions and generate no heat. Did you know that cycling is the most energy efficient mode of transport?

Efficiency is the perfect use of water. Polluting potable water with waste such as sewerage and chemical cleaners requires energy and further chemicals to restore the water to a usable state. Efficient water usage means reducing consumption and leaving it in a usable state. Reducing waste and chemicals entering the water system means more efficient processing of water. Processing waste on site (composting toilets, greywater systems) reduces both waste and water consumption.

Solar energy is time efficient. Oil and natural gasses are the result of thousands of years of energy from the sun. Using the sun directly is an efficient time short cut.

Increasing crop yields makes more efficient use of space. Decreasing the use of fertilizers moves towards the perfect balance of an efficient ecosystem. Growing food near where it will be consumed is transport efficient. All our environmental goals centre around efficiency.

We need to learn from nature – waste nothing, strive towards perfect efficiency.

The first Cape Town green bloggers get together is happening this Saturday, 11 Oct at 14h00. If you are a green blogger in Cape Town then join Juliana Rotich, Environment Editor of Global Voices Online, and other local green bloggers for an informal gathering. You can find all the details and RSVP on the wiki. Unfortunately I am unable to make it, but I am really glad that this is happening. Thanks Rory!

Every time information is duplicated there is the possiblity of an error. Let me say that again, every time information is duplicated there is the possibility of an erorr.

The electronic design process is made up of different parts such as schematic capture, PCB layout, component procurement and assembly. Each step requires information to be passed backwards and forwards. Certain information is only relevant to particular steps, for example you only need the exact part number for ordering, while a more basic part number or description could be used in the schematic (passives like resistors and capacitors are a good example of this).

Deciding what is important amongst all this information can be difficult, which often results in much of the information being duplicated in each step. The tools we use for electronic design automation (EDA) can inadvertently encourage us to create duplicate parts with detailed information contained within them. This seems fine until the parts library grows to an unmanageable size and discrepancies start to creep in, resulting in design and manufacturing errors.

Passing information between different systems, like the stock management and design systems can create an even larger mess. Typically these two systems are separated from each other and keeping them synchronised becomes a full time job. Any discrepancies between the two systems result in expensive time losses due to incorrect stock. The more information there is to keep track of, the greater the chance of errors and wasted time and money.

I am sure that most engineers have at some point in their career come across massive stock and bill of material spreadsheets which are overwhelming to manage, not just due to the amount of information, but also due to the incorrect tool (a spreadsheet) being used.

Yes, there are probably comprehensive ERP systems that can help with these problems, but those are not necessarily accessible to small engineering firms or individuals.

Information duplication is the enemy of efficient systems, we must eliminate it wherever possible.

That is the first rule of the process that I am developing for my own business. It will help me to develop faster and better, and once it is working it is going to allow every engineer access to the same opportunities.