Ben’s Blog

For about two months now, I’ve been spending most of my spare time reading and doing experiments out of Make: Electronics. My spare time has dwindled now that I’m back to teaching and taking classes. It’ll dwindle even more as I get into semester projects.

I’m now up to Experiment #16 in Make: Electronics; about half way through. I’ve learned a good bit, even though the book is definitely aimed at newbies. I have skipped a couple of experiments that didn’t seem like they offered enough new experience for the amount of effort they would require.

I would recommend the book to anyone with one disclaimer: be prepared to spend a lot on tools and supplies. I’m also not terribly fond of the author’s recurring intruder alarm example. I feel like he could have come up with a better project. On the other hand, I don’t know of a better hands-on, beginner’s guide to electronics.

For now, I’m suspending my efforts on the book to finish up my DDS-60 card. More on that soon.

I started playing around with electronics about a year ago. You can make do with a breadboard for a while, but if you stick with electronics long enough you’ll eventually get around to soldering. I actually started soldering kits right off the bat, but I agonized over what gear to buy. I agonize over any major purchasing decision (and most non-major ones), so this isn’t new for me. I’ve been very happy with my gear, so I thought I’d share it to make the decision-making process a little easier for others. I’ve been meaning to post about my gear for a while now, but actually tinkering with electronics has taken priority. Last week a friend of mine mentioned he was looking at buying a soldering iron and related gear, so I thought it was time to finally get around to it.

I got a Circuit Specialists Soldering Station for $45. It’s a 40 watt temperature-controlled station. I have the one with the digital temperature display, but they have an analog version for $5 less. The analog one is more than accurate enough, but I like the digital look. It comes recommended by others, and I have no complaints. The grip on the iron gets a little hot, but not to the point of being uncomfortable. I’ll probably upgrade eventually, but I expect it’ll be several years. You could probably get by with a non-temperature-controlled iron, but I think this one is definitely the best bang for buck.

For through hole work I use a 1.2mm chisel tip. Most people would probably use the next size up, but I enjoy the extra control the smaller tip gives you. For surface mount work I use a 0.8mm conical tip.

I decided on 63/37 Kester 285 solder, in 0.031″ diameter for through hole and 0.015″ diameter for surface mount. The 63/37 refers to the percentages of tin and lead in the solder. The 285 refers to the type of flux. Flux helps the solder stick to the objects you’re trying to solder. While solder sticks to metals like copper very well, it doesn’t stick to oxides very well. Unfortunately, the high temperatures involved in soldering cause accelerated oxidation. Flux helps prevent oxidation and also serves as a wetting agent, causing the solder to flow. Some fluxes must be cleaned off the board after soldering. I don’t have time for that, so I settled on Kester’s 285, the most active flux I feel comfortable leaving on a board. There are also “no clean” fluxes, but they tend to not perform as well. Especially while you’re learning to solder, stick with something like Kester 285. You can also get lead-free solder, but it’s not beginner friendly either.

I bought my solder from Digikey in 1lb. spools. It runs $20-30 per spool.  It’s hard to find good solder in small amounts. Radio Shack has small quantities of solder, but I have no idea if it’s any good. If you’re just getting started in this hobby I’d be glad to give you some solder. There’s no way I can use it all before it goes bad. (This type of solder has a shelf life of three years or so.)

I also have a flux pen, but I’ve only used it a couple of times when hand soldering surface mount ICs.

You need a way to clean your soldering iron’s tip. Most irons come with a cheap sponge that you wet. I use a Hakko 599B tip cleaner. It looks like a pot scrubber, but it has flux on it that cleans your tip. It also doesn’t drop the temperature of your tip like a wet sponge.

Sometimes you need to remove solder. There are two basic ways to do this: a desoldering pump or desoldering wick. The pump seems to be the old standby, but I’ve had way more luck with wick. I never use the pump these days. I use TechSpray wick and it does a good job. I use size #3 for through hole components and size #2 for surface mount.

I use Xcelite 378M pliers and 170M shear cutters. Amazon has them for $14 as a pair. You can make do with a small pair of regular pliers, but cutters like this are virtually essential. Home Depot carries an identical set under the Cresent brand.

Good lighting is essential for this sort of thing. While not ideal, I use a Petzl headlamp when soldering. Magnification is also important. I have a 10x jeweler’s loupe that I use for checking joints after the fact. I’d love to have a lamp/magnifier combo that clamps to my desk, but they’re expensive, and I’m sure my kids would find a way to break it. One of those magnifier visors would be nice too.

So, yes, getting setup to solder is a little on the expensive side, but it’s not bad compared to a lot of hobbies, you don’t have to buy it all at once, and it’s a good skill to acquire. Let me know if you have any questions.

I started building electronic kits about this time last year. (My grandmother got me a soldering iron for Christmas.) At this point I’ve built several kits, but I’ve only gotten around to posting about a couple of them. This kit, the NorCal Dummy Load was my third project, the first being the MintyBoost, and the second being a AVR microcontroller programmer that I haven’t had a chance to post about yet. More on that one later. I built this kit back in February of 2009. You can see all the photos here.

Dummy load in vise, on desktop.

So, what the heck is a dummy load? When you’re testing a transmitter, you can’t just transmit without anything connected to the output. You could fry your final amplifier. So you need a dummy load that presents the correct impedance, 50 ohms in most cases. As it just so happens, I’m getting ready to build a transceiver, and will need a dummy load for testing. Also, this particular dummy load involves several surface mount (SMT) parts, and I wanted a little practice with those before beginning my next project, the Softrock Lite II 30m software-defined receiver.

This kit was designed and sold by NorCal QRP, a low-power (QRP) ham radio club based in Northern California. They have put together several kits over the years. They actually retired this kit a couple of years ago, but I inquired on the qrp-l list and someone had one they weren’t planning on building.

Some hams are intimidated by surface mount (SMT) components, and rightly so; they’re pretty small. Have a look below. The small black thing to the right of the penny is a 2.2 kOhm SMT resistor. SMT components come in different sizes. This size is referred to as 1206, which means it’s 0.126″ × 0.063″. It’s one of the larger sizes of SMT components.

As it turns out, soldering SMT components isn’t too bad. I used a small tip on my soldering iron and small solder (0.015″ diameter) and had no problems. There were no SMT integrated circuits on this project, but there would be on my next project.

Tonight I started on another SMT project, but using solder paste, a griddle, and an embossing gun instead of solder and a soldering iron. More on that later.