This is part-2
(please have look at http://vu3inj.blogspot.in/2014/01/dds-vfo.html)
5volts and 3.6 volt power supply for ebay module
all diodes are 1N4007, C1 and C2 are 100mfd,25volt electolytic capacitor. voltage regulator is LM7805.
resistors are 68k, all diodes are 1n4148
four dip switch. DIP switch has 8 on/off individual switch in miniature.
I have soldered the 16pin ic pad and on that mounted the dip switch.
All the diodes are connected with dip switch as shown on the w4 . For the clarities sake i have not drawn the other diodes.
74hc04 is gate. 74hc4017 is a counter ic.
work is in progess and there is still some glitches. i am little strained at present and hope to redo this module in future.( what i mean by glitch, setting of freq is not perfect, low freq osc is wobbling changing its own freq and thus effecting the modules output freq.....)
please note:-
It is tiresome to work on simple vero board, if you want to try please make a proper pcb.
it has the limitations also,
its a fixed frequency type.
you have to tweak a little to run it on your exact desired frequency.
buffer after the ebay module is needed.
some sort of shielding for rf is needed.
but, with this ckt you will be able to test your bunch of ebay modules.... so, it does not replace any pic, processor based ckt but it complements and where beacon is to be run or only wants to be on afixed freq this is a good and cheap options,
IT DOES NOT WORK
AS OF 06 MARCH 2014 .
Anyone wants to try please let me known your outcome, so i also change my ckt accordingly and thank you.
This is second part the PREVIOUS ARTICLE IS http://vu3inj.blogspot.in/2014/01/dds-vfo.html
