Your Electronics Workbench

The Basics

First, you’ll need a breadboard. You can call it a “prototyping board,” but this is like calling a battery a “power cell.” Search RadioShack online for “breadboard” and you’ll find more than a dozen products, all of them for electronics hobbyists, and none of them useful for doing anything with bread.

A breadboard is a plastic strip perforated with holes 1/10″ apart, which happens to be the same spacing as the legs on old-style silicon chips — the kind that were endemic in computers before the era of surface-mounted chips with legs so close together only a robot could love them. Fortunately for hobbyists, old-style chips are still in plentiful supply and are simple to play with.

Your breadboard makes this easy. Behind its holes are copper conductors, arrayed in hidden rows and columns. When you push the wires of components into the holes, the wires engage with the conductors, and the conductors link the components together, with no solder required.

Figure A shows a basic breadboard. You insert chips so that their legs straddle the central groove, and you add other components on either side. You’ll also want to buy a matching printed circuit board (PCB) that has the same pattern of copper connectors as the breadboard.

First use the breadboard to make sure everything works, then transpose the parts to the PCB, pushing their wires through from the top. You immortalize your circuit by soldering the wires to the copper strips.

Soldering, of course, is the tricky part. As always, it pays to get the right tool for the job. I never used to believe this, because I grew up in England, where “making do with less” is somehow seen as a virtue. When I finally bought a 15-watt pencil-sized soldering iron with a very fine tip (Figure C), I realized I had spent years punishing myself. You need that fine-tipped soldering iron, and thin solder to go with it.

You also need a loupe, a little magnifier (Figure D). A cheap plastic one is sufficient. You’ll use it to make sure the solder you apply to the PCB hasn’t run across any of the narrow spaces separating adjacent copper strips, creating short circuits.

Short circuits are the #2 cause of frustration when a project that worked perfectly on a breadboard becomes totally uncommunicative on a PCB. The #1 cause of frustration (in my experience, anyway) would be dry joints.

Any soldering guide will tell you to hold two metal parts together while simultaneously applying solder and the tip of the soldering iron. If you can manage this far-fetched anatomical feat, you must also watch the solder with supernatural close-up vision. You want the solder to run like a tiny stream that clings to the metal, instead of forming beads that sit on top of the metal. At that precise moment, you remove the soldering iron. The solder solidifies, and the joint is complete.

You get a dry joint if the solder isn’t quite hot enough. Its crystalline structure lacks integrity and crumbles under stress. If you’ve joined two wires, it’s easy to test for a dry joint: you can pull them apart easily. On a PCB, it’s another matter. You can’t test a chip by trying to pull it off the board, because the good joints on most of its legs will compensate for any bad joints.

You must use your loupe to check for the bad joints. You may see a wire-end perfectly centered in a PCB hole, with solder on the wire, solder around the hole, but no solder actually connecting the two. This gap of 1/100″ is enough to stop everything from working, but you’ll need a good desk lamp and magnification to see it.

A Few Components and Tools

Just as a kitchen should contain eggs and orange juice, you’ll want a variety of resistors and capacitors. Your neighborhood Shack can sell you prepackaged assortments, or you can shop online at mouser.com or eBay.

After you buy the components, you’ll need to sort and label them. Some may be marked only with colored bands to indicate their values. With a multimeter (a good one costs maybe $50) you can test the values instead of trying to remember the color-coding system. For storage I like the kind of little plastic boxes that craft stores sell to store beads.

For your breadboard you’ll need hookup wire. This is available in precut lengths, with insulation already stripped to expose the ends. You’ll also need stranded wire to make flexible connections from the PCB to panel-mounted components such as LEDs or switches. To strip the ends of the wire, nothing beats the Kronus Automatic Wire Stripper, which looks like a monster but works with supernatural efficiency, letting you do the job with just one hand.

Needlenose pliers and side cutters of various sizes are essential, with perhaps tweezers, a miniature vise to hold your work, alligator clips, and that wonderfully mysterious stuff, heat-shrink tubing (you’ll never use electrical tape again). To shrink the heat-shrink tube, you’ll use a Black and Decker heat gun.

If this sounds like a substantial investment, it isn’t. A basic workbench should entail no more than a $250 expenditure for tools and parts. Electronics is a much cheaper hobby than more venerable crafts such as woodworking, and since all the components are small, it consumes very little space.

For completed projects you need, naturally enough, project boxes. You can settle for simple plastic containers with screw-on lids, but I prefer something a little fancier. Hammond Instruments makes a lovely brushed aluminum box with a lid that slides out to allow access. Grooves inside the box accept a printed circuit board. My preferred box has a pattern of conductors emulating three breadboards put together. This is big enough for ambitious projects involving multiple chips.

Learn the Rules

Read a basic electronics guide, like my Make: Electronics (makershed.com), to learn the relationships between ohms (Ω), amperes (A), volts (V), and watts (W), so that you can do the numbers and avoid burning out a resistor with excessive current or an LED with too much voltage. And follow the rules of troubleshooting:

Look for dead zones.

This is easy on a breadboard, where you can include extra LEDs to give a visual indication of whether each section is dead or alive. You can use piezo beepers for this purpose, too. And, of course, you can clip the black wire of your meter to the negative source in your circuit, then touch the red probe (carefully, without shorting anything out!) to points of interest.

If you get an intermittent reading when you flex the circuit board gently, almost certainly you have a dry joint somewhere, making and breaking contact. More than once I’ve found that a circuit that works fine on a naked PCB stops working when I mount it in a plastic box, because the process of screwing the board into place has flexed it just enough to break a connection.

Check for short circuits.

If there’s a short, current will prefer to flow through it, and other parts of the circuit will be deprived. They’ll show much less voltage than they should.

Alternatively you can set your meter to measure amperes and then connect the meter between one side of your power source and the input point on your circuit. A zero reading on the meter may mean that you just blew its internal fuse because a short circuit tried to draw too much current.

Check for heat-damaged components.

This is harder, and it’s better to avoid damaging the components in the first place. If you use sockets for your chips, solder the empty socket to the PCB, then plug the chip in after everything cools. When soldering delicate diodes (including LEDs), apply an alligator clip between the soldering iron and the component. The clip absorbs the heat.

Tracing faults in circuits is truly an annoying process. On the upside, when you do manage to put together an array of components that works properly, it usually keeps on working cooperatively, without change or complaint, for decades — unlike automobiles, lawn mowers, power tools, or, for that matter, people.

To me this is the irresistible aspect of hobby electronics. You end up with something that’s more than the sum of its parts — and the magic endures.