Measure Temperature With the Arduino and the MC9700A

Tim, N9PUZ writes:


A while back you mentioned your club built up some of the bare bones Arduino boards. I’ve been using the Arduino for a while. Recently I needed to measure some temperatures. I discovered the Microchip MCP9700A in a TO-92 package. It’s $0.36 in single pieces from Mouser and will measure -40C to +120C.

I wrote an Arduino library for the MCP9700A sensor that’s released under a GPL license.The library functions will provide either Celsius or Fahrenheit temperatures for as many sensors as you have ADC ports. If anyone is interested they can download a copy from my blog.

There is an installable library, source code, and an example program.


Tim, N9PUZ

Very cool. Thanks, Tim!

New Kit from 4SQRP

Terry, WA0ITP, reports:

The Four State QRP Group is very pleased to announce the availability of our new AAØZZ EZKeyer kit.

This full featured PIC-based iambic keyer features 3 memories, 12 direct entry commands, and is very user friendly. It has many of the features of the high end keyers while maintaining ease of use. The PIC chips have been programmed by
Craig Johnson, AAØZZ, of PIC-EL fame.

There are only 10 parts to install on the quick build pc board, and the extensive manual features an Altoids installation tutorial.

The kit is is reasonably priced at only $17.

Please check out the details and order information at

Thank you for supporting the Four State QRP Group and OzarkCon.

Make: Newsletter is Back

The Make: magazine newsletter is back. To be honest, I didn’t realize that it had stopped coming, but looking at the website, it looks as though the last issue was published on January 30, 2009.

I’m glad it’s back. This issue has some interesting stuff, including these tips originally posted on Twitter:

  • A drop of hot-melt glue or candle wax diffuses too-bright LEDs nicely, and is easily removable. (via @unixbigot)
  • Drop a small item (e.g. smt resistor) on the floor. Put some pantyhose over your vacuum’s tube….it will suck it up, but won’t eat it!

You can subscribe to this e-mail newsletter by going to

Stuart’s First Kit

Many of you are familiar with Stuart, KD8LWR, my newest Elmeree. Since visiting us at Field Day, he’s gotten his ticket and made many contacts on 2m FM and EchoLink, and we’re working on how to get him on HF CW.

Well, yesterday was another milestone. He attended his first ham club meeting and built his first kit. Yesterday, we built things at the ARROW meeting.

We started Stuart out with a Wee Blinky kit from DaleWheat.Com. This is a great little kit for beginners. It consists of 11 components—two LEDs, four resistors, two capacitors, two transistors, and a 9-V battery snap. There are only 24 solder joints to make.

I had to show Stuart how to form the leads and insert the components, and I also showed him how to solder them to the board. These steps were a bit awkward because I didn’t think about providing some kind of fixture for holding the board. That really would have been a help for someone building his first kit.

Even so, Stuart did a great job, and when we connected the battery, it worked! That’s more then I can say about the first kit I built.

Plug for Dale Wheat
Since Dale Wheat donated a bunch of the Wee Blinky kits to the recently-held A2 MiniMaker Faire, and ARROW benefited by getting passed a few of the extra kits, I thought I’d give Dale a plug here. Thanks, Dale!

Dale has another kit that may be of interest to radio amateurs. His Smart Battery Meter “measures the ‘state of charge’ of a 12 volt or 24 volt sealed, lead-acid battery system. It uses a multi-color array of LEDs to give an instant visual indicator of the remaining charge, sort of like a gas gauge.”

Another FB Construction Project

RevEBreadboard800Last night, my ham radio club, ARROW, held its annual construction night. As reported earlier, we built Bare Bones Board Arduinos, the cute, little microcontroller shown at right.

A dozen guys built one, and all but one got them working. I’m not sure why, but he decided to troubleshoot his Arduino at home.

Perhaps the most challenging part about building the kit was mounting the surface-mount inductor. The technique that I, and most of the other guys used, was to tin the pads, hold down the component with either a tweezers or needle nose pliers, and then reflow the solder. One guy had a heckuva time doing this as the component markings were slightly misprinted on his board, with the ink covering those pads. Carefully scraping off the ink with an X-acto knife remedied that situation.

Several people commented, “They’re cute, but what can you do with one of those things”? Well, the latest issue of QEX has an article that uses the Arduino as a keyer. As I noted in the previous blog post, I have an idea to use mine to interface a paddle to my computer, so that I can send code to the computer instead of typing on a keyboard. Another crazy idea I had was to hook a solenoid up to one of the outputs and key a straight key connected to a rig.

Of course, there are a bunch of other possible uses, including controlling a remote antenna switch and monitoring power supply or battery outputs. There are dozens of other applications outside the shack as well.

Of course, being ever vigilant for topics for future club meetings, the answer to the question, “What can you do with an Arduino”?, is now on our schedule. Next January or February, we’ll have a talk about a) how to program the Arduino and b) what one ham did with his.

ARROW’s September Construction Project

Every September, our ham radio club, ARROW, does a construction project. In the past, we’ve done a keyer kit, J-Pole antennas, and other small projects that you can complete in an evening.

Bare Bones BoarduinoThis year, we’ve decided to build a low-cost version of the Arduino microcontroller called the Bare Bones Boarduino, from Modern Device. This is a pretty good introductory soldering project.

What’s an Arduino (or Freeduino)? It’s an open source microcontroller board that is cheap ($11), and fairly easy to program from Linux, a Mac, or even Windows. You program it in “C”, and there are libraries other folks have written to let you do things like run servos, blink LEDs, and so on. The Bare Board Boarduinos use the ATmega328Phave processor and have 32k flash memory and 2k of RAM.

What can you do with an Arduino or Boarduino? Well, you can check out the Arduino website for ideas.

In addition, the September/October 2009 issue of QEX contains a story on how to use the Boarduino to build a keyer. I don’t really need another keyer, but that article, coupled with an idea gleaned from the Ten-Tec-Omni-VII mailing list has given me an interesting use for the Boarduino, I think.

The mailing list thread discussing the 610 got my creative juices flowing is the thread discussing the elusive Ten-Tec 610 Remote Keyer. I say “elusive” because if you search the Ten-Tec website for information on this product, all you’ll find is a press release that says it will cost $169 and that it will be available sometime in 2009. There are no product specifications or photos to be found anywhere.

This dearth of information has, of course, led to a lot of speculation about what it will do and what it won’t do. Carl, N4PY, seems to have the most information on this product. He writes:

This keyer will interface through a USB port and become an additional keyboard for the computer. Paddles will plug into it and operating the paddles will cause the 610 keyboard to send characters to the application that has the focus just as though the characters were typed on a regular keyboard. There will also be a provision to add the Ten-Tec remote tuning pod to this device. Turning the knob left or right will cause certain special characters to be sent to the application that has the focus. The application will realize a right turning or left turning operation from the 610 keyboard and take appropriate action. So all programming will simply look at the receiving characters to figure out what to do.

This all sounds very cool, but $169 seems kind of steep. I’m guessing that I could program the Boarduino ($10 hardware cost, plus the cost of some kind of USB port) to interface to my computer so that I could use paddles instead of a keyboard for text input. Wouldn’t that be cool?

My iMac currently uses a USB keyboard, so I’m guessing (hoping?) that I won’t have to write a driver for the Mac end. Anyone know where I can find interfacing information for the Mac USB port?

Surplus Sources

From the mailing list, here’s a list of places that sell surplus electronics and other stuff that might be of interest to ham radio operators:

In trying to verify these links, I also ran across the Web page, Surplus Electronics and Equipment for Amateur Scientists. It has quite a bit of stuff, and looks relatively up-to-date.

Tin Whiskers 101

tinwhiskerTin whiskers can be real killers for electronics equipment, especially for electronics using no-lead solder. This primer on tin whiskers has all the basic information you need to know, including:

  • what they are,
  • what causes them, and
  • what you can do to avoid them.

WD8DAS Searches for Heathkit

While his family went to the beach, WD8DAS visited the sites of the old and new Heathkit plants in St. Joseph, Michigan.

Connector/Cable Wiki Helps You Make Connections

Thanks to Frank, K0BRA, for pointing this out via the AMRAD mailing list. He writes:

Now there is a Wiki on connector pinouts [and cable wiring]. If you are into making cables to hook this to that and need pin numbers you may find this makes it quick and easy. There is a lot of obscure stuff out there and this is the place to find it. If you don’t, then add it.

Looks like a good resource, and because it’s a wiki, you can add connector pinouts and cable wiring lists that aren’t there. Shall we start a ham radio cable category?