Hello,

I’ve been looking for an easy and inexpensive way to generate sine waves up to 10-15 MHz. The best solution I’ve found so far is an AD9850 DDS which is claimed to produce stable sine waves of up to 30 or 40 MHz by many hobbists and expermenters. Vp-p drops to about %80 of the max amplitude at the frequecies I would use but it’s no problem.

I want to amplify the DDS output to drive some coils (solenoid and other shapes).

The only thing I know about digitaldevices is that they work on square waves. I’m a total newbie here.

I found two easy ways to make the DDS work.

1- Connect an Arduino between the DDS and the PC. Upload the ready-made codes to Arduino. Enter the frequency.

2- Connect the DDS directly to the PC. Use a software like “WA6UFQ "DDS Controller" to make it work.

Simple as they may sound, taking these options to practice is still beyond anyone with no practical experience. I can’t find anything about some questions probably because I don’t know where or how to look for (google). Such as:

1- Arduino is easily plugged into the USB port . But how could I connect the AD9850 to the serial port of the PC. I think my laptop has no printer port.

2- At the output of the DDS, I will need to amplify the voltage. I guess the op-amps have the advantage of adjustable amplification ratio versus the transistor amplifiers (like common emitter). That advantage would really come handy for me. But I have to find a way to match the input impedance of the op-amp with the DDS output. The AD9850 datasheet is full of unfamiliar terms and names and I can’t figure this out. I found an example given below.

3- What kind of wire or cable should be used to make the PC-DDS-Amplifier or the Arduino-DDS-Amplifier connections (between the pins).

Thank you for reading this.

 

The DDS hooks up to a micro and talks SPI (some may talk I2C?). The micro usually hooks up via USB.

Those DDS chips usually have a demo board that you can buy with a micro that they have developed the drivers for so you can just plug and play. It is a little pricey though (probably around $120 for the whole thing). Otherwise, those DDS chips can be quite a bear to do, especially if you have no prior experience (they take something like 28 bit instructions...pretty intimidating for a beginner, but not impossible). The other good news is that I am pretty sure someone probably made an Arduino library for a similar chip in the family. You seem to already have that portion covered.

If the the output is a voltage output, you can use any opamp provided it will work in the frequency and gain your specify. If it is a current output, it is a little more involved, but not that much. I would not worry about impedance matching just yet. Just get the thing to work. That kind of is another subject in itself.