Electronics > Projects, Designs, and Technical Stuff
Home Brew Analog Computer System
robrenz:
I am still following GK, great stuff :-+
c4757p:
Me too!
But mathematically perfect sine? What am I missing? Looks parabolic to me.
GK:
--- Quote from: c4757p link=topic=12331.msg378294#msg378294 --- What am I missing? Looks parabolic to me.
--- End quote ---
Nothing at all; I just shouldn't post after midnight on a workday, lol.
Yes, it is of course parabolic and that (sin/cos terms) results in a circle which is more like a square with broadly rounded corners. That rules it out, along with the logarithmic shaper.
I guess I'm left with breakpoint-shaping.
C:
Hi
Are you making creating a time base circle too hard?
Look at the video of dave cal of the time base.
Just create a Sine wave for your time base, one cycle equal one sweep.
The default amplitude of which is the circle size.
Do a second Sine wave with 90 degree phase delay or add a 90 degree phase delay to the first.
You have your X an Y base.
Great timebase with no retrace time.
Think what would be the vert on scope is the input to two voltage-controlled amplifiers with the gain controlled by the X & Y above.
http://www.google.com/patents/US3047767
here is a quick find, real new stuff (1932)
Have you seen a radar scope.
Great for knowing what is around you but not real great for telling the direction. If you start at the outside edge with greater distance to the center, easer to read direction while harder to get the great picture understanding.
One use I recall the time base was the circle close to the outer edge of the tube with vert of normal scope being a radial deflection to or past the center of tube.
Some had a huge display with very long persistence.
I do remember that when used the circle display was much better then normal scope display.
Radio direction finding was one use.
Think I remember something about radio signal analyst.
Been to long for a lot of details, sorry.
Think the big selling points was the very long trace with no retrace time.
C
GK:
--- Quote from: C on January 31, 2014, 06:03:19 am ---Hi
Are you making creating a time base circle too hard?
Look at the video of dave cal of the time base.
Just create a Sine wave for your time base, one cycle equal one sweep.
The default amplitude of which is the circle size.
Do a second Sine wave with 90 degree phase delay or add a 90 degree phase delay to the first.
You have your X an Y base.
--- End quote ---
Sure, but that wouldn't be a true triggered timebase. What you describe is exactly what I did for my Fourier synthesis character generator, but that is an entirely different application.
A true triggered time base is important as you want the "sweep" synchronized with the input signal, just like in any other scope.
If I wanted to do it the simplest way possible, I would just make an injection-locked state variable (quadrature) oscillator. However that would have major functional limitations - the timebase sweep time (and amplitude!) could not be calibrated and synchronization could only be had with input signals that are frequency multiples of the timebase oscillation frequency.
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