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help needed for project of Xbee adapter

by laurar on Sat Jul 14, 2012 6:56 pm

I`d like to try to duplicate (starting on a breadboard) the Adafruit XBee wireless modem adapter (or a similar one ).
But the scheme in the product page is too difficult for me : can anyone help with indications on how to biult it , obviously buying all the component needed separatley?
Thanks
Laura
laurar
 
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Re: help needed for project of Xbee adapter

by jpbot on Sun Jul 15, 2012 9:00 pm

Hello,

You didn't link to the item you are referring to, nor mention what parts of the schematic were too difficult. I'll take a stab at trying to answer and hopefully it should get you steered in the right direction.

Unfortunately the XBee pins are closer together than a standard perfboard, protoboard or breadboard spacing will allow. Something like the XBee adapter is basically required to allow prototyping on a breadboard.

I'm looking at the schematic here: http://www.ladyada.net/images/xbee/xbee11sch.png

The schematic should be pretty simple. The only thing I see that might throw a beginner for a loop is IC2, a 74AHC125N chip. The 74AHC125N is a quad bus buffer (though in searching I see mention of it being discontinued so you might need to find an alternative if you're looking to build your own version of the adapter). The purpose of the 74AHC125N is to interface the about 5v levels with the XBee which requires 3.3v levels. It is shown in the schematic as IC2A, IC2B, IC2C, and IC2D for the separate gates.

For alternatives you might look at http://www.adafruit.com/products/735 (74LVC245) or CD4050.

IC1 is a 3.3 volt regulator and I know some beginners see the TO-92 package part and expect it is a transistor, in this case a voltage regulator.
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