Re: [DIYbio] fancy waveform generator?

What you want is going to depend a lot on your application.

Square and Sawtooth waves are easy to generate, sines are a bit harder but
still not bad. By 'arbitrary' do you mean you want to be able to sum up
squares and saws and sines to form a waveform? Would a, for example,
circuit that can sum up 8 channels (so you can use a fourier series to
approximate your waveform) work? Would summing up square waves work?

Or do you literally want to be able to apply arbitrary voltages in series
with smooth transitions in between?

Another important consideration: How high of frequency do you need? Doing
arbitrary waveforms (connect-the-dots style) is easy in the 1-10 kHz
range; it's MUCH more difficult if you need to do it in the 100 kHz - 10+
MHz range. Same goes with power -- low (signal-level power) is easy, high
power (> 1 amp) is harder.

If you just want a general purposer arbitrary waveform generator (does
sines/squares/saws/pulses/etc.) Rigol has an affordable model (Rigol
DG1022) for about $400-$500 that goes up to 20 MHz.

If you're looking for something a bit more DIY-style or extensible, the
Exar XR2206 is a good chip to start with. I have never used it myself but
have heard good things about it.

If you're looking for connect-the-dots style waveform control, using a
microcontroller is a good way to go. You can digitally put your "dots"
together with an Arduino (you can digitalWrite() at ~200 kHz safely) or a
LeafLabs Maple to go up faster (I think 10 MHz is doable). From there on
out you can use pulse amplitude modulation and filters to get a smooth
analog waveform. Pulse Width Modulation + filtering can also get you
where you want to go depending on your application.

$0.02

nathan lachenmyer

On Fri, 8 Jun 2012, Raymond McCauley wrote:

> I'm looking for a waveform generator, one that's not just restricted
> to sine/square/sawtooth, but is able to generate a wave of arbitrary
> complexity, preferably under computer control. So either a fancy
> oscilloscope, or a piece of hardware that interfaces to a computer.
> One that works in KHz regimes.
>
> Do you have any ideas? A favorite catalog you could point me to?
>
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