From Geoff's Projects Blog comes the Maximite BASIC computer.  It looks like an interesting bit of kit and the table of contents at the blog has some other interesting topics.

The Maximite is a small and versatile computer running a full featured BASIC interpreter with 128K of working memory.

It will work with a standard VGA monitor and PC compatible keyboard and because the Maximite has its own built in SD memory card and BASIC language you need nothing more to start writing and running BASIC programs.

The Maximite also has also 20 input/output lines which can be independently configured as analog inputs, digital inputs or digital outputs.  You can measure voltage, frequencies, detect switch closure, etc and respond by turning on lights, closing relays, etc - all under control of your BASIC program.

The design and the firmware including the BASIC interpreter is free to download and use.   And all this is powered by a single chip which costs just US$8.44.



The Maximite was described in the March, April and May 2011 issues of Silicon Chip magazine. 

The mini Maximite was described in the November 2011 issue of Silicon Chip magazine. 

If you have not read the articles you can find out all you need to know by clicking on the links below:

• Maximite Features and Capabilities
• Maximite Design and Construction
• Maximite BASIC
• The mini Maximite

Check out the rest of the article at Geoff's Projects.

Since I first saw Mikal Harts Reverse Geocache Puzzle I knew I needed to build one. My best mate and his wife are avid GeoCachers (is that a word?) and I decided to make a special gift for his 30th birthday. Well, I missed that particular deadline, but never mind, better late than never eh buddy!?

Having seen lots of other people try their hand at it in their own unique interpretations I had a few ideas of my own in mind. At the top of the list I wanted my Geocache to be more flexible than most.

There are a lot of useful tools on-line.  I got busy and organized some of the ones I use often.  Perhaps you'll find these useful.  Please share others that you use.

I installed these in the bookmark toolbar in Firefox. 

Save to Parts List

Bookmark for Arena PartSaver to organize components in a Google Docs spreadsheet

DigChip IC Database
Datasheet, cross-reference and functional listing of integrated circuits

FindChips
Locate integrated circuits

Resistor Value Table
Table of standard values

RadioShack is starting to get some nice products but sadly, they are not well described on the package or on the web site.  I took a leap of faith and purchased this test lead set and I'm quite pleased with it.  The set is called a "Micro-scale Test Lead Kit" part number 2780039 and costs $20.  The package has a little information on it but it's lacking in details such as what these leads are supposed to connect to.

Let's start with the first question.  What is the lead connection?  The leads are designed to fit standard test lead probe tips.  Personally, I would have preferred that they fit banana jacks but this is ok.  The picture below shows the set.

In Power Protection Circuits, I outlined some methods of circuit protection.  In this article, I'll take a closer look at the practical aspects of using a P-Channel MOSFET circuit for reverse polarity protection.

Both the series diode and crowbar circuit have been seen to have some rather large limitations.  This circuit isn't any more complex and yields substantially improved performance.

I used an IRF-9630 P-Channel MOSFET that I had on hand for this test.  This is a 6.5 amp, 200 volt unit with an R_DS resistance of 0.8Ω.  A MOSFET with a lower R_DS would be a better choice but this unit will illustrate the principle.