building/homebrewing

According to the website Fritzing.Org:

Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to take the step from physical prototyping to actual product. We are creating this software in the spirit of Processing and Arduino, developing a tool that allows users to document their Arduino and other electronic-based prototypes, and to create a PCBlayout for manufacturing.

Despite the wacky name, this looks like very cool software. Just avoid using the phrase, “I’m fritzing around with this circuit.” Someone’s going to have to develop a module for Manhattan-style layout, though.

Watch this video:

Robert Lacoste writes The Darker Side column in Circuit Cellular, and now he has published a book, Robert Lacoste’s The Darker Side: Practical Applications for Electronic Design Concepts from Circuit Cellar. Topics covered span digital signal design to avoiding interference. EETimes’ RF Designline has published an excerpt from Chapter 4, which covers oscillators. There are five parts:

1. Introduction to oscillators, including piezoelectricity and how a crystal works.
2. How to adjust a crystal, depending on whether it is to be used as a parallel resonant frequency element or a series resonant element.
3. A classic quartz-based CMOS oscillator.
4. How to accurately determine oscillator start up time and stability.
5. What happens at higher frequencies (overtone mode)?

Here’s a Make: magazine video on the Jameco Electronics website that shows you how to build circuits on perfboard and talks about the different types of perfboard that are available. Despite the fact that the narrator seems very nervous, it’s a good video explaining how to do this.

Jameco has a lot of different types of perfboard available. At left, you can see a perfboard that measures 1.6-in. x 2.7-in., which will fit nicely into an Altoids tin. It seems a bit expensive at $5.49, but it will make building a circuit easier to do, and if you don’t like what you built, you can always remove (carefully) the components and try something else.

Two years ago—almost to the day—I wrote about making a min-solder pot to tin toroid leads. Well, now I finally have one.

Sunday, at the museum, Jim, K8ELR, brought down all of the soldering irons he’d ever purchased to try them out in building the little QRP transceiver kit he just bought. The results of that may be the topic of another blog post, but one of the irons he had was a 25 W Weller pencil iron.

“Aha,” I thought, “this would be perfect for the mini-solder pot.” I convinced Jim to let me take the iron home with me and convert it by noting that his kit had several toroids whose leads were going to need stripping and tinning.

I  did that tonight. I carefully hacked off the end of the soldering iron tip and filed it down. Then, I carefully drilled a 5/64-in. hole about 3/16-in. deep. I then widened the hole to 3/16-in. The hole in the tip wasn’t exactly centered, but I didn’t break through the sidewall of the tip.

I plugged in the iron, heated up the tip, and filled it with solder. I dipped a short piece of enameled wire, and a couple of minutes later, I had a perfectly tinned lead! It had worked like a charm. In about 15 minutes, I had eliminated one of the most odious tasks associated with kit building. This is going to be well worth the effort.

Here’s a great tip from the 6/23/10 ARRL Contest Update:

Uh-oh! You dutifully cleaned off all of your vacuum tubes to make them shiny and the numbers came off with the dirt! Pat AA6EG saves the day – “Put the tube in the refrigerator, cool it down, then bring it into a warm room temperature environment. There will be moisture condensing on the glass envelope, sometimes leav[ing] a readable outline of the tube numbers.”

If you have any tubes at all in your junkbox (mine’s more like a junk closet), you’ll undoubtedly have some that you can’t identify.

On the QRP-L mailing list, a ham asks:

I know this should be a simple answer, but I’m having a hard time finding it. I am interested in building a EFHW coupler similar to the one on AA5TB’s site. He uses #22 AWG magnet wire.

I’m interested in using something less stout which I have on hand (e.g., #27 AWG magnet wire). Is there a calculator to determine how this would affect the number of turns on the transformer, or am I incorrect in thinking that it would make a difference?

Diz, W8DIZ, replied:

No calculator that I know of.

1. Smaller wires have less current capacity before heating – bad thing.
2. Smaller wires have less capacitance between windings (if same # of turns) – good thing.
3. Wire size (for all practical purposes) does not determine inductance.