Ahh, I love those opamps! I saw that TI has come out with an 'improved' version. 5nv of voltage noise and 12 MHz GBW, but 7pF of input capacitance. (not good for PD front ends.)
They should work just fine. Is the power supply well filtered? 100uF alum. or 10uF ceram.
Tim W. (above) had a good description of avalanche zeners. Near the knee the noise is biggest. If you're a bit above or below the knee there is a voltage asymmetry with higher voltages towards the knee (it changes sign depending if you're above or below).
On a sunny day (Fri, 4 Jun 2010 20:21:47 -0500) it happened "Tim Williams" wrote in :
I get: You tried to access the address
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which is currently unavailable. Please make sure that the Web address (URL) is correctly spelled and punctuated, then try reloading the page. Make sure your Internet connection is active and check whether other applications that rely on the same connection are working.
The magnets are there to make ionized-gas filaments break up (otherwise the thyratron would latch ON just like its 'normal' operation instead of just amplifying noise). That, at any rate, is the explanation I heard four decades back...
I know you operate your own server, which is prone to occasional bouts of downtime (which are presumably your responsibility, as admin... these things happen, it's a fact of life), but it's rather preposterous for you to project that assumption onto others. I certainly do not run this server myself.
Indeed, please note that the server is the Milwaukee School of Engineering webspace, which is held by the school. I have absolutely no part in its uptime or maintenence. Indeed, the outage was scheduled summertime maintenence, which was announced on the mailing list (which you wouldn't know about, but could reasonably assume).
Please do not jump to faulty conclusions in the future. Your conversations will go more smoothly.
Tim
--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
I'm sure the university has more than a single server. Their network traffic can be divided in a number of different ways to balance the load. Even a typical 'home' grade of broadband router can direct different ports to different computers.
--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
Yes, they are very nice. But ... I replaced the opamps with TLE2237's, and it fixed the problem. The higher gain-bandwidth product of the TLE2237 (50 MHz vs. 8) seems to have done the trick. I don't understand exactly why, but it worked, so I'll keep it. ;)
The OPA2134 is more optimized for high slew rate, and its low distortion spec is not only published, but hard to beat at the price. I normally use them at much lower gain, so have no problems with frequency response in the audio band.
With the TLE2237's still saw a drop of nearly 1 dB at 40 KHz, but at that point I suspected that it was due to the combination of audio cables, sound card and software, so I did a loopback test, using a software white noise generator. And with that, I got almost exactly the same spectrum -- I set Spectrum Lab to the highest level of averaging and smoothing, and the plots of the loopback "wire" and the white noise generator agreed almost pixel-perfect. In the plot,
1 pixel was 0.1 dB, so I am done. I cannot make the circuit work any better with the tools I have at hand.
I looked at that, and moving to larger, 100 uF caps did quiet the supplies a little, but I didn't see any difference in the spectrum.
Yes, it was, and thanks for that! It was better than what I read at Wikipedia or anywhere else. Good stuff, and I think I'm starting to understand.
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