"Joerg"
** Though 20 Hz is nominally an "audio" frequency - it is not the audio band, which extends up to 20kHz.
> What would be a really low noise FET? Should be well under 10nV/rtHz at
> the lower end of the audio band, say at 20Hz.
So your heading is quite wrong.
You are after a low noise at low frequency JFET.
........ Phil
Ok, yes, it's more sub-audio what we are after. IOW where animals like whales "sing".
Yep, and unfortunately the specs are often skimpy. There seem to be some nice Panasonic parts like the 2SK2593 but not much in the datasheet. Looks like we'll have to try them all out.
"Joerg"
** I just gave you the one to look for - with full specs.Around 2 nV /rt Hz at 20 Hz.
....... Phil
On a sunny day (Tue, 13 Nov 2007 13:06:30 -0800) it happened Joerg wrote in :
As to the defense of the BF245, yo useem so sure it 'noisy' at LF. I have never seen that, but have not really looked for extremes either. Here is a nice circuit, look at the table on page 4
Yes, I meant most others. I'll ask the guys to buy some 2SK369 at Ampslab. Toshiba also has a nice dual: 2SK3320. For some reason the main distributors don't seem to carry Toshiba. Strange.
"Jan Panteltje"
** Utterly irrelevant to the OP's stated requirement.He wants low voltage noise, in a low impedance circuit at sub audio frequencies.
....... Phil
"Joerg"
** This mob have the similar 2SK170 for 53 cents in 50 up....... Phil
Thanks. The 2SK369 you suggested earlier is even better and Ampslab has it. Right now it's ok to buy anywhere, we'll wory about quantities later. Toshiba has never been a problem in that respect but last time I used their FETs was in Europe where there are (or were?) a lot more smaller distributors. Don't know how it is in Australia but here in the US it's mostly Arrow, Allied and so on, the big ones.
On a sunny day (Wed, 14 Nov 2007 08:48:12 +1100) it happened "Phil Allison" wrote in :
Says you.
'Natural radio' is from practially DC to a few kHz. As to the impedance, I dunno what he wants. He is VERY secretive. maybe EEG (maybe he makes EEG of horses :-) ).
It'll be a few hundred ohms.
Well, I am not at liberty to tell. But it's not for horses :-)
"Joerg"
I can literally walk out of my front door and up the street for about 200 metres to a component's dealer who will sell me 2SK369s $1.20 Australian each.
Likely half that price if I want 50 or 100 of them.
........ Phil
"Jan Panteltje" "Phil Allison"
** Well f*ck you - Mr Arrogant Smartarse.** But not sub audio at low Z. ** Makes you an even bigger ass.
The OP specified a noise voltage of 5 nV /rt Hz at 20Hz - consistent with impedances below 1000 ohms.
** But not stupid like you........ Phil
Nice, but you live in Sidney which is a huge city. You can do the same in New York. But out here in the boonies I can walk down the street and, without delay, they'd sell me glow plugs and tractor oil for the John Deere, horse feed, saddles, cowboy boots, a Stetson hat ...
On a sunny day (Wed, 14 Nov 2007 09:24:07 +1100) it happened "Phil Allison" wrote in :
Seek help.
"Jan Panteltje"
** F*ck off - you crazy wog IDIOT !!........ Phil
On a sunny day (Wed, 14 Nov 2007 09:51:27 +1100) it happened "Phil Allison" wrote in :
I have been down under, but only as far south as Melbourne. I did not know it got so bad further south. Guess I was lucky.
"Jan Panteltje"
** F*ck the HELL off -you asinine, crazy wog IDIOT !!
...... Phil
...and poison to get rid of the Phil Allison's in the grass ;-)
...Jim Thompson
You poor, downtrodden people who live in such crowded locations. I can literally walk out my front door and go about 200 meters, and still only be halfway down my driveway. ;-)
"DJ Delorie"
** Nice rural sanatorium you live in - eh ?........ Phil
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