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1750Hz tone decoder

Thanks to Patrick TK5EP for work on this alternative to the LM567 on the repeater controller board.

When retuning the 567 to 1750Hz he found that drift was a problem so he adapted some work by “LargeMouthBass” on this site http://www.instructables.com/id/Frequency-Detector-using-PIC-12F683-Processor/

Patrick’s webpage is here: http://www.tk5ep.tk/

There is no point in me repeating his work. I suggest you use the links above to see what has been done. You may need to click on the small British flag at the top left of the page to show his site in the language you need.

Patrick’s add on for DTMF with a PIC micro