lose down this news group.
in [Basics]
|
From: John Larkin on 26 Apr 2010 19:04 On Mon, 26 Apr 2010 12:08:42 -0700 (PDT), terryS <tsanford(a)nf.sympatico.ca> wrote: >Looks like this news group has gone the way of some others. > >It's inundated with advertising; for Gucci and Rolex cheap copies, >imitation or over-stock Nike shoes etc. doubtful services or site >references and so on. > >So it's now virtually useless for it's original purpose. i.e. >discussion of basic electronics and allied matters. > >Personally make a point of NEVER contacting or buying anything from >any one of these advertising interlopers to what once was a useful >discussion group. > >Anyone agree? Bye the bye ...................... goodbye! My usenet provider and spam filters do a pretty good job of keeping the junk down. That said, there's little actual activity left. John
From: George Herold on 26 Apr 2010 23:19 On Apr 26, 3:08 pm, terryS <tsanf...(a)nf.sympatico.ca> wrote: > Looks like this news group has gone the way of some others. > > It's inundated with advertising; for Gucci and Rolex cheap copies, > imitation or over-stock Nike shoes etc. doubtful services or site > references and so on. > > So it's now virtually useless for it's original purpose. i.e. > discussion of basic electronics and allied matters. > > Personally make a point of NEVER contacting or buying anything from > any one of these advertising interlopers to what once was a useful > discussion group. > > Anyone agree? Bye the bye ...................... goodbye! OK, I still like this group. Here's today's problem. I was measuring the power supply noise that was feeding my input opamp. And when I did that the noise went down! opamp was opa134 with 1uF film cap to the power supply rail and 10k ohm to ground. The power supply came from a switcher ~100kHz, I have a ~30kHz LC filter in front of it(100uH torroids and ??? tantalum caps.), followed by a two pole capacitor multiplier. (2N4401/3..2N3904/6's oscillated too much.) 1 kohm, and 100uf Al electro. in parallel with 0.1 uF ceramic. The noise went down from ~8 nV/rtHZ when the 1uF cap was connected to ground to about 5% lower... 7.7 nV/ ... Maybe I should start hanging 1uF metal films everywhere? George H.
From: Michael Black on 26 Apr 2010 23:28 On Mon, 26 Apr 2010, John Larkin wrote: > On Mon, 26 Apr 2010 12:08:42 -0700 (PDT), terryS > <tsanford(a)nf.sympatico.ca> wrote: > >> Looks like this news group has gone the way of some others. >> >> It's inundated with advertising; for Gucci and Rolex cheap copies, >> imitation or over-stock Nike shoes etc. doubtful services or site >> references and so on. >> >> So it's now virtually useless for it's original purpose. i.e. >> discussion of basic electronics and allied matters. >> >> Personally make a point of NEVER contacting or buying anything from >> any one of these advertising interlopers to what once was a useful >> discussion group. >> >> Anyone agree? Bye the bye ...................... goodbye! > > My usenet provider and spam filters do a pretty good job of keeping > the junk down. That said, there's little actual activity left. > Now I know why the post sounded familiar, it's more than simply because we see such posts from time to time. Back on January 8th of this year (2010) the same poster posted about spam, posting nonsense and even suggesting this newsgroup be "closed down". That explains the subject header this time around, he isn't taking nonsene but "close down this news group". So like I said, he isn't paying attention. Probably this is the first time since then that he's looked in here. Michael
From: John Larkin on 27 Apr 2010 00:20 On Mon, 26 Apr 2010 20:19:25 -0700 (PDT), George Herold <ggherold(a)gmail.com> wrote: >On Apr 26, 3:08�pm, terryS <tsanf...(a)nf.sympatico.ca> wrote: >> Looks like this news group has gone the way of some others. >> >> It's inundated with advertising; for Gucci and Rolex cheap copies, >> imitation or over-stock Nike shoes etc. doubtful services or site >> references and so on. >> >> So it's now virtually useless for it's original purpose. i.e. >> discussion of basic electronics and allied matters. >> >> Personally make a point of NEVER contacting or buying anything from >> any one of these advertising interlopers to what once was a useful >> discussion group. >> >> Anyone agree? Bye the bye ...................... goodbye! > > >OK, I still like this group. Here's today's problem. I was measuring >the power supply noise that was feeding my input opamp. And when I >did that the noise went down! opamp was opa134 with 1uF film cap to >the power supply rail and 10k ohm to ground. The power supply came >from a switcher ~100kHz, I have a ~30kHz LC filter in front of >it(100uH torroids and ??? tantalum caps.), followed by a two pole >capacitor multiplier. (2N4401/3..2N3904/6's oscillated too much.) 1 >kohm, and 100uf Al electro. in parallel with 0.1 uF ceramic. Emitter followers love to oscillate when the base impedance is low. The fix is a series base resistor, or a ferrite bead if you're afraid of Johnson noise. This is an energetic, ballpark 100 MHz oscillator: +10 | | | c +5----------------b most any NPN e | +----------out | 1K | | | gnd > >The noise went down from ~8 nV/rtHZ when the 1uF cap was connected to >ground to about 5% lower... 7.7 nV/ ... Maybe I should start hanging >1uF metal films everywhere? > >George H. The OPA is spec'd for 8 nv/rthz typ, so you're about there. Most opamps have really ratty PSRR at high frequencies, so a clean supply is mandatory. John
From: Sjouke Burry on 27 Apr 2010 00:46
George Herold wrote: > On Apr 26, 3:08 pm, terryS <tsanf...(a)nf.sympatico.ca> wrote: >> Looks like this news group has gone the way of some others. >> >> It's inundated with advertising; for Gucci and Rolex cheap copies, >> imitation or over-stock Nike shoes etc. doubtful services or site >> references and so on. >> >> So it's now virtually useless for it's original purpose. i.e. >> discussion of basic electronics and allied matters. >> >> Personally make a point of NEVER contacting or buying anything from >> any one of these advertising interlopers to what once was a useful >> discussion group. >> >> Anyone agree? Bye the bye ...................... goodbye! > > > OK, I still like this group. Here's today's problem. I was measuring > the power supply noise that was feeding my input opamp. And when I > did that the noise went down! opamp was opa134 with 1uF film cap to > the power supply rail and 10k ohm to ground. The power supply came > from a switcher ~100kHz, I have a ~30kHz LC filter in front of > it(100uH torroids and ??? tantalum caps.), followed by a two pole > capacitor multiplier. (2N4401/3..2N3904/6's oscillated too much.) 1 > kohm, and 100uf Al electro. in parallel with 0.1 uF ceramic. > > The noise went down from ~8 nV/rtHZ when the 1uF cap was connected to > ground to about 5% lower... 7.7 nV/ ... Maybe I should start hanging > 1uF metal films everywhere? > > George H. You might also check for very high frequency oscilation. Changes occurring when you barely tough a circuit is the first symptom. |