John Curl's Blowtorch preamplifier part II

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scott wurcer

scott wurcer

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Joined 2004
jacco vermeulen said:
As a fan of both, my envelope is bungy stretching back and forth, i'm still waiting for stress fatigue to step in.

Mr W,
speaking of folklore revisited, so i take it your back is not covered with Japanese Yakuza tattoo's and you haven't done frequent runs to Havana on a Cigarette power boat with loads of AD797, in exchange for genuine Cuban Cohibas ?
(i never know what to believe from those Scully and Mulder characters)
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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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simon7000

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Joined 2008
scott wurcer said:
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.
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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
 
john curl

john curl

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Joined 2003
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.
 
john curl

john curl

Member
Joined 2003
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.
 
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Jacques Merde

Jacques Merde

Member
Joined 2009
john curl said:
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.
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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.
 
Cal Weldon

Cal Weldon

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calweldonconsulting.ca
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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. ;)
 
Jacques Merde

Jacques Merde

Member
Joined 2009
john curl said:
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.
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To quote Hans Landa, "That's a Bingo!"
 
Jacques Merde

Jacques Merde

Member
Joined 2009
Cal Weldon said:
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. ;)
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Uh, oh. I'm on the police radar now :)

Je ne comprende pas Jacques Merde.
 
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