1
Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude
« Last post by Terry Bites on Today at 03:39:24 pm »That DDS chip has an output stabilty quoted as "200 ppm/°C" not great, but then DDS is aimed at RF where no one cares much about precise amplitudes.
DIY your own DDS:
Back in the day, before low cost microcontroller platforms and social media had been dreamt of, I made a sine source for an LVDT sensor using a lookup table on a M27C1024 eprom (still to be found on ebay and in my 90's junk box), some counters (74LS590 i think) and an AD669 (still available) with a REF01 10v reference. That was 16 bits of rock solid 10v pp waveform! No control loop rubbish to worry about. For your puposes a very simple antialias filter is needed to polish off any clock residues. Of course you can easily tune it up using the counter's clocks. Add your own precsion attenuators and gain. Feels good....
I think a pwm source driven by code or from a lookup table could do just as well. Precision clamp the PWM amplitude, nice lowpass filter, job done. The Arduio can create 16 bit PWM using its internal timers. Sine dump here www.daycounter.com/Calculators/Sine-Generator-Calculator.phtml
DIY your own DDS:
Back in the day, before low cost microcontroller platforms and social media had been dreamt of, I made a sine source for an LVDT sensor using a lookup table on a M27C1024 eprom (still to be found on ebay and in my 90's junk box), some counters (74LS590 i think) and an AD669 (still available) with a REF01 10v reference. That was 16 bits of rock solid 10v pp waveform! No control loop rubbish to worry about. For your puposes a very simple antialias filter is needed to polish off any clock residues. Of course you can easily tune it up using the counter's clocks. Add your own precsion attenuators and gain. Feels good....
I think a pwm source driven by code or from a lookup table could do just as well. Precision clamp the PWM amplitude, nice lowpass filter, job done. The Arduio can create 16 bit PWM using its internal timers. Sine dump here www.daycounter.com/Calculators/Sine-Generator-Calculator.phtml