January 1st, 2014 by Chris Elwood
I've recently been working on moving from AVR to STM32 microcontrollers for most of my projects. While AVRs were great to learn on, they aren't the best value compared to the other options available now. For the price you can generally get a a STM32 chip with more power and better peripherals.
So far I have mostly worked with the STM32 Discovery boards because they are cheap and include the programmer. But they are somewhat large and not breadboard friendly. What I really wanted was something simple to replace an Arduino as the "standard" board I use to test out new ideas.
Here is what I ended up with:
There is not much to it beyond the basic components needed to get things running. This is partly because I am new to board design and wanted to keep it simple. But it is also all I really need to replace an Arduino in most projects. Total cost to build one is under $10 even in small quantities.
Programming using the built-in programmer on a discovery board.
Here are the eagle files.
May 3rd, 2013 by Chris Elwood
Some time in the last year my VX-6R radio started having problems receiving. On narrowband FM mode it had trouble picking anything up at all. The local weather radio station, which came in loud and clear on another radio, could barely be heard. I did some searching around and found this forum thread which described exactly the same problem. Then, while looking for the replacement part mentioned there, I found a description of the same fix here.
Conveniently, the second page above was written by Tim (WO9U), who is part of the amateur radio club at my school. I asked him about it and found out that he even had a spare of the replacement part! So today I opened up the radio and took care of it. The details are better explained in the links above, but basically it came down to replacing a filter that had failed. Tim was kind enough to not only provide the replacement part, but to bring his soldering equipment for me to use and to help with the actual repair. Having someone experienced watching certainly helped with the nervousness of taking a soldering iron to a relatively expensive radio!
After removing bad filter. (empty box above the yellow connector)
The only difficult part was removing the old filter, which took almost an hour. It should have been easier, but the soldering iron used was not meant for lead free solder and probably was not as hot as would be ideal for this.
New filter in place and ready to go back into the radio.
The replacement seems to have completely fixed the problem! Full signal strength on the weather radio station again and background noise is back to a normal level.