A little while ago I picked up an AD9850 DDS board. Basically, these are little boards you can pickup on eBay for about $10 shipped that can be programmed to output a sinusoidal wave from 1hz to about 40mhz. The output is about 1Vp-p and is fairly clean.
To drive these little boards you have to program them using either a serial interface or a parallel interface. You send over a couple of bits according to a code specified in the spec sheet and the AD9850 outputs the appropriate frequency.
I used an Arduino UNO board, LCD 16×2 display, and a rotary encoder to create a little all-in-one VFO. It can output the full range available to the AD9850 but I simply limited it to only 7.0-7.3Mhz in the Arduino code. I will be using the VFO as part of a DC receiver I am putting together for fun.
You can see a video of it in action here: http://youtu.be/r6nRMikOOmI
The code to drive the AD9850 is fairly simple, however, the hardest part I found was getting the large integer (frequency) split up into the appropriate numbers to display on the LCD screen. Some creative code fixed that problem. Full documents and discussion on this item is on the permanent page located here.
I was browsing a couple of websites I frequent and I ran across a posting of a guy making his own parts for projects using something called “InstaMorph”. After I read a little about Instamorph I knew I had to get my hands on some.
This stuff is mold-able plastic. Basically, it is these tiny little pellets that you place into almost boiling water (150F or so). After a minute or so they become clear, soft, and malleable. You can then shape and mold the pellets into whatever you like and when it cools down it becomes hard again. I have no idea what in the world I am going to use it for but if the need arises to make something… I’m ready!
I’ve been searching the cheap electronics on eBay lately and I ran across a couple of items that look interesting. One of those items is an Analog Devices 9850 Square/Sine wave 1-40mhz signal generator. What makes these things amazing is that they can be purchased for about $10 and that includes shipping. So… I bought one! It arrived and I was a little shocked at how small this little device actually is.
I have an Arduino that I just starting tinkering around on so my hope is to get the Arduino to drive the AD9850 and see what kind of oscillator I can make. There are some other people who have already done this so I should be able to borrow some code rather than start from scratch. Unfortunately my AD9850 arrived without any pinout schematic so I have to track that down first.