Reading the part number or date code on an electronic component package gets harder and harder as electronics get smaller and smaller and my eyes get older and older.
Magnifying glasses and optical loupes are fine for quick views and short-term work. But, they’re awkward to use for long periods of time, such as when you’re sorting a bunch of surface-mount components or inspecting a large batch of circuit boards.
Low-end digital inspection microscopes (or video microscopes) can cost several hundred dollars even on eBay. Industrial or manufacturing-quality scopes are much more expensive. However, as you'll soon see, most amateurs already have the basic parts to make their own do-it-yourself microscopes or video inspection tools.
I store all of my electronic parts in plastic containers with adjustable compartments.
Plastic adjustable storage case (Archer #64-522 from RadioShack).
Recently, when removing an organizer box from the storage cabinet, I didn’t see the smaller container on top of it. Everything happened in slow motion from the moment I realized that the falling container held tiny surface-mount parts (SMD/SMT). “Nooooooooooooo!”.
Although my best one-handed attempt to catch the box was unsuccessful, I did manage to control the descent enough to prevent the contents from spraying everywhere. Nevertheless, the lid lifted enough that many parts got mixed up and some spilled out.
As you can see in the above photograph, the majority of the parts stayed in their individual cubby holes. So, I didn’t want to make things worse by dumping out the entire container to sort it from scratch.
Because they’re so tiny, it is difficult to pick up SMT (surface-mount technology) electronics by hand. God help you if you drop them into carpeting! (This is a good time to remind readers that my office will never qualify as a “clean room”.)
A large neodymium rare-earth magnet easily transports a pile of SOT-23 transistors.
Rare-earth magnets (like those made of neodymium) can grab small electronic parts from quite a distance. Simply waving the magnet over the spill area extracted most of the electronic parts, even out of cracks and crevices.
A magnet also works well for lifting components out of individual container compartments or moving a large pile on a tabletop. This is how I was able to pull groups out of their compartments without having to dump the whole box.
Old-fashioned ferric kitchen magnets are generally too weak to be useful for this task. Instead, spend $15 to pick up a decent-size powerful neodymium-iron-boron magnet (NdFeB) from eBay or an online surplus / scientific seller.
DIP chips have adequate surface area to silkscreen a legible part number label. But, many modern electronic parts like SOT-23 transistors have only a couple of millimeters or less to print a unique identifier. It was going to take far too long to sort hundreds of tiny electronic parts using a magnifying glass, not to mention the strain from being hunched over a table.
What I needed was something that magnifies just enough to be able to read the labels of multiple parts simultaneously, while sitting comfortably.
A homemade digital video inspection apparatus with a tripod, video camera, TV monitor, desk lamp, tweezers, and black construction paper.
Most consumer video cameras have pretty decent macro zoom and focusing capabilities. Attach the video camera to a cheap tripod or choose whatever mounting method works for you.
Each camera model is going to have an optimal distance at which it can zoom in but still stay in focus. Some cameras include a macro-focus button that looks like a flower.
Good lighting is required for the part labels to be readable. A desk lamp with an adjustable goose neck allows you to aim the light in a manner that highlights the labels. Direct overhead lighting can sometimes result in too much reflection.
Sorting black parts with dim printing is best done on a dark non-reflective surface like black construction paper. Anti-static foam contains too many pits and holes that the electronic leads and corners will catch on -- making it difficult to slide parts into their respective groups.
Although you could use any stiff instrument for sorting, tweezers allow you to nudge a part, pick it up, or turn it. If you don’t have a nice pair of electronics tweezers, you can save some money by searching for deals such as 5 stainless-steel tweezers for $5 from All Electronics (#TW-5).
Lastly, the most important piece for magnification is a television or computer monitor with a standard NTSC or S-video input.
Using a video monitor to read the markings on a batch of SMD transistors and selecting one with tweezers.
The larger the video monitor, the greater the magnification of the image. But even my dinky old 10″ monitor that I dragged up from the basement was satisfactory for sorting most components. For better results, go over to your friend’s house and sort components in front of their 60″ plasma flat-panel.