Actually, the ceramic caps are the worst of it. The follower is OK, but I would simplify it to just a jfet follower. It would sound OK, and not be easily affected by RFI.
I think the author found 10% distortion in this circuit under some conditions. You will also notice this is used as a two pole low pass. The author recommended a two pole Sallen Key. I would add that this done with a modern high speed single supply bi-FET would be fine and RFI resistant.
I'm afraid I don't smoke and I'm afraid of needles. But I do have proof that everyone is an artist.
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A 2 pole Sallen Key low pass filter could also be easily done with a jfet follower. The only significant change would be about 6 dB less total output, which I consider inconsequential.
Scott,
I think all the rational folks are generally in agreement. Any particular device you would suggest?
I can only really think of ones to avoid! The low supply voltage won't let my old standbys shine.
I reserve the right to pick everyone else's brains and then publish any good results as entirely my own work!
ES
Ahh . . . in other parlance The Brain Produces a Poor Autobiography Michael Gazzaniga The Ethical Brain.
Nice one Scott.
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Jacques, do you really think that the rolloff of a 2 pole Sallen Key Bessel-Butterworth filter would be seriously compromised by the use of a single fet follower, rather than an IC? Be careful, I designed my first 5 pole Sallen Key Butterworth filter using a pair of transistors in 1968, and it went into subsequent production without problems.
Sorry about asking you about your name, I was really serious, because sometimes this sort of name coincidence happens, especially between different languages.
Sorry about asking you about your name, I was really serious, because sometimes this sort of name coincidence happens, especially between different languages.
Hard to believe that someone with even little knowledge of French would consider it a real name .... 😉
PMA, sometimes it happens. Back in olden times, I worked with Iranian college students who were shocked at our employer's last name. It meant something really pornographic in their language. However, on consideration, Jacques name could have been an American translation of not knowing very much as in: 'I don't know: Jack Sh-- about that subject.'
A phrase usually in reference to someone else.
A phrase usually in reference to someone else.
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Well, with a standard 2 pole Sallen Key configuration, I would expect
stopband attenuation to be in the -50dB to -60DdB range, given JFETs
like 2SK170 and reasonable values in the feedback network. Higher gm
parts like BF862s would improve that a bit. Of course, there are
methods to deal with the leakage, but they mostly involve additional
active circuitry.
The real question to me is if the decreased stopband attenuation will
be significant for this application.
Merde, according to my French friends isn't really the brown stuff that English speakers want it to mean, it is more intended to mean Oh crap! or Oh Shoot!
as in:
Merde!, Je suis en retard pour le souper.
Oh crap!, I am late for dinner.
Until someone complains about it, I don't see it as a problem myself. Mind you I don't give a merde about a lot of things. 😉
as in:
Merde!, Je suis en retard pour le souper.
Oh crap!, I am late for dinner.
Until someone complains about it, I don't see it as a problem myself. Mind you I don't give a merde about a lot of things. 😉
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