DDS VFO with ARDUINO.
The original article is being published by VU3ELR , OM SHASHI. he was one of the instrumental organizers for the Ham Fest India 2014 at Hyderabad.
Read the article published in the HFI2013 suverniours. The ino files and ckt is missing but article might inspire you.
How open source can be beautiful and smart.have a look.
The wheel is borrowed from the VU3ELR. If you like it make it. All credit (and blame) goes to him.
The original article is being published by VU3ELR , OM SHASHI. he was one of the instrumental organizers for the Ham Fest India 2014 at Hyderabad.
Read the article published in the HFI2013 suverniours. The ino files and ckt is missing but article might inspire you.
How open source can be beautiful and smart.have a look.
DDS
VFO
Sasi
– VU3ELR
A
few years ago, many of us faced the problem
of constructing a stable vfo for RM 96s, with
limited or no access to calibration equipment I had
aligned my VFOs with great difficulty. With the lack of
availability of Styroflex capacitors and NPO capacitors it has become
very difficult to make a stable vfo. Being a starter, home-Brewer, I
used to search the net for many alternative ideas to make a stable
rock bound vfo and finally landed up with no progress as I got QRL
with my professional activities.
Although
QRL, I never stopped thinking of a good stable vfo that could be used
with my RM- 96. I went surfing the net for various solutions and did
a little work on some DDS circuits. There are number of circuits
available using AD9850, AD9851, Si570..Etc controlled by PIC and
other chips. All these circuits are found to be programmed using ASM,
Micro C. They need some knowledge in the languages if we intend to do
any minor changes to work for our applications. With little bit of
working knowledge on these DDS VFOs, I finally thought of developing
a DDS VFO that can be programed/modified by an average Home-Brewer.
Like
a lot of Hams, while browsing for electronics on eBay I came across
some of these super inexpensive DDS modules being sold that
could be shipped from China (for about Rs.500/-) These modules
are are far cheaper than the DDS 9850 chip which costs
around Rs.1300. . OM Paddy, VU2PEP initiated the idea and
encouraged me try out a DDS with this module I had no second thought
and immediately started working on it and ordered a
pair of modules and received the same in less than a weeks’ time
The
Circuit:
Before
embarking on this circuit I would like to say that none of
these ideas are mine and are taken various
references and sources available from well defined
circuits of pioneers in home brewing. In this circuit, I have paired
my Home-Brew Arduino Uno with AD9850 module purchased online from on
EBay, a 16X2 LCD display, Rotary encoder, and a few other small parts
put together making a very descent DDS VFO capable of any frequency
between 1Mhz and 30Mhz. The easiest way to manage the AD9850 is
with an Arduino Uno. A little quick work with a proto-board and
I had a nice working VFO. The schematic shown below is a little
rough and I tried my best to make you understand. The circuit is a
straight forward and simple and with a little knowledge on
Arduino IDE, The VFO is easy to brew as short notice
“ before you complete your Coke” you can have the up and
running HI
A
word about Arduino:
Arduino
is an open-source electronics prototyping platform based on flexible,
easy-to-use hardware and software. It's intended for amateurs,
designers, hobbyists and anyone interested in creating interactive
objects or environments. Arduino can sense the environment by
receiving input from a variety of sensors and can affect its
surroundings by controlling lights, motors, and other actuators. The
microcontroller on the board is programmed using the Arduino
programming language and
the Arduino development environment. Arduino projects can be
stand-alone or they can communicate with software running on a
computer. The boards can be Home-Brewed or purchased a
preassembled and the software can be downloaded for
free. The hardware reference designs are also available under
an open-source license; you are free to adapt
them to your needs.
If
you need to know more about the Arduino platform you should check out
the official site at www.arduino.cc. I have been playing with
the Arduino for only a couple of months and I already found it to be
a fantastic development platform.
PCB
Layout and Arduino sketch:
As
the source code is unable to put on paper, the required PCB Gerber
Files and the Arduino sketch is available on request via mail
s4sasi@gmail.com. The low pass filter is directly taken from RM-96.
The values of T1, C1 and C2 will change as per the desired operating
frequency.
Acknowledgement:
I
specially thank OM Paddy, VU2PEP for initiating the idea and giving
me a support to complete the circuit. I would also like to thank
VU2BVB, VU2CJV, and VU2ZAZ and may others for their valuable feedback
and literature.
So,
finally there’s no reason why you too cannot have a economical and
a efficient DDS VFO for peanuts without slogging and
compete with hams running commercial transceivers and work most
of the digital modes which was beyond the working of a homebrewed
analog vfo. This DDS VFO can be used as a plug-in replacement for the
VFO many old commercial and valve transceiver like the
HW101 SB102 etc and also as useful signal source for the bench,
or as an LO for a direct conversion transceiver … the possibilities
are endless!
Happy
Home-Brewing.
The wheel is borrowed from the VU3ELR. If you like it make it. All credit (and blame) goes to him.