Friday, July 18, 2014

Simple RF Source

As an aside while waiting for parts and boards I thought I would post a quick note about a previous project that worked well and turned out to be very useful as well as a good learning exercise with tools, instruments, and QFN construction techniques.

Prior to the availability of the Beagle Bone Black, my basic approach was to use 2"x2" boards with PIC microcontrollers and a USB interface.  In some of the posts there are references to a Prj114.  This was a simple ADF4351 with PIC control interface.  All together it costs about $30 (depending on how you count the PCB cost).  It uses the Analog Devices reference design as a starting point.  You can see the pads were not pulled out on the QFN part which caused me a great deal of trouble.  It is still useful as a quick and flexible standalone source.

Simple synthesizer using a PIC and ADF4351
Early on I started a practice of adding a small logo or drawing on the silk screen layer.  I read about some of the elaborate logos and illustrations people submitted with their OSHpark boards.  It turned out to be a quick visual identification when you have several purple PCBs lying around.  I continued it as it caught the attention of my family members and piqued their interest in what I was doing (even if they didn't care about phase noise measurements and PLL lock times).  The symbols are thought of at the last moment as I'm trying to get the PCB finalized.  Lacking any other inspiration and significant artistic ability, I generally choose something I can draw and involves a recent holiday, season, or activity.  In the case above Valentine's day.

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