Hi,
I built up a MAX038. I get a sine wave with the peaks slightly skewed. Does not matter what frequency it is set to.
The supply voltages are +/- 4.92V.
What causes this slight shift? Any ideas what to look for?
I used this circuit:
www.kitsrus.com/pdf/k101.pdf
Thanks.
I built up a MAX038. I get a sine wave with the peaks slightly skewed. Does not matter what frequency it is set to.
The supply voltages are +/- 4.92V.
What causes this slight shift? Any ideas what to look for?
I used this circuit:
www.kitsrus.com/pdf/k101.pdf
Thanks.
Attachments
You need to lift pin 7 (DADJ) from GND and make it adjustable between a volt or so pos and neg - something like the FINE adjust but then between + and -. That will let you adjust the symmetry of the waveform.
One way to test it is to look at the square wave output (NOT the sync output - that is always 50%) and adjust as best as possible for 50% duty cycle.
It's all in the data sheet, by the way...
Jan Didden
One way to test it is to look at the square wave output (NOT the sync output - that is always 50%) and adjust as best as possible for 50% duty cycle.
It's all in the data sheet, by the way...
Jan Didden
thanks. I will give that a try. I wonder how the kits they sell get away without having to make that adjustment. I'm using all the same values and parts.
Doesn't look like a symmetry problem. I'd rather say there is some leak from the square wave to the sinewave, perhaps caused by charge injection or something similar.
Might be caused by a poor layout, or it could happen internally in the MAX038. Even if this is the case you could correct it by injecting a square of opposite phase into the sine output, through a high value resistor f.e.
Might be caused by a poor layout, or it could happen internally in the MAX038. Even if this is the case you could correct it by injecting a square of opposite phase into the sine output, through a high value resistor f.e.
Looking at it again, it may well be the graph itself. The line is quite thick and jumps one or two pixels at the time.
What equipment/program did you use to make it? If you look on the scope, do you still see those jumps? Probably not!
Jan Didden
What equipment/program did you use to make it? If you look on the scope, do you still see those jumps? Probably not!
Jan Didden
actually, I just cut and pasted a sine wave from the wave
to show as an example of what I see on the oscilloscope 🙂
my respects to your great attention to detail. 😉
I had the max 038 part so I wanted to give it a try.
it's working but not great so I need to spend some more
time on it.
to show as an example of what I see on the oscilloscope 🙂
my respects to your great attention to detail. 😉
I had the max 038 part so I wanted to give it a try.
it's working but not great so I need to spend some more
time on it.
Bengali said:
So maybe there isn't a problem at all. Maybe a pic of the scope screen would be more clear.
Jan Didden
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