2N3819 source

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Is there anything uber-"magical" about that particular part?

According to OnSemi's datasheet at least, the parameter variation is wide. Not to mention, no noise specs of any sort, of anything "interesting".
https://www.onsemi.com/pub/Collateral/2N3819-D.PDF

For what it's worth, a while ago i got a whole bunch of FairchildSemi J305's from Bernard Loffet (two batches, in fact).
https://groupdiy.com/index.php?action=profile;u=49295

No idea whether he has any more available, though.
And looks like he hasn't been around here since sometime last year, but his website is www.sonotrad.org - probably easier to get a hold of him that way.

http://vakits.com/sites/default/files/J305.pdf
 
I had two options. Mouser and buy 5000 or eBay.

I had to take a punt on eBay. I’ve spent countless hours searching and come up with nothing. They haven’t arrived yet but when they do I’ll gladly let you know where from if they’re genuine.

Seems like a pretty closely guarded secret, this place has changed.
 
I'm pretty sure NTE has some in stock. I bought a few last year:

https://www.ntepartsdirect.com/ENG/PRODUCT/2N3819

I bought some last year to have as backups. I still had some NOS Fairchilds so I used those in my builds, but the NTEs tested out with good quality.

 
Ricardus said:
I'm pretty sure NTE has some in stock. I bought a few last year:

https://www.ntepartsdirect.com/ENG/PRODUCT/2N3819

I bought some last year to have as backups. I still had some NOS Fairchilds so I used those in my builds, but the NTEs tested out with good quality.

Unfortunately don't post to Australia!
 
For what it's worth, the BF245 datasheet seems to have very similar numbers to the 2N3819...

https://www.onsemi.com/pub/Collateral/BF245A-D.PDF
 
"For what it's worth, a while ago i got a whole bunch of FairchildSemi J305's from Bernard Loffet (two batches, in fact).
https://groupdiy.com/index.php?action=profile;u=49295"

I'm sorry to say that sadly,  Bernard Loffet has passed away. His wife informed me of this , and told me she has no intention nor the competency to pick up where he left off.
 
Oh, dang :( That's unfortunate... Granted, i haven't dealt with him all that much, but he's been helpful and great when i did.

RIP...

fsalter said:
"For what it's worth, a while ago i got a whole bunch of FairchildSemi J305's from Bernard Loffet (two batches, in fact).
https://groupdiy.com/index.php?action=profile;u=49295"

I'm sorry to say that sadly,  Bernard Loffet has passed away. His wife informed me of this , and told me she has no intention nor the competency to pick up where he left off.
 
I do not understand why everyone is so obsessed with 2N3819's. Here's the table from National Semiconductor FET databook with process 50 Jfets. As it can be seen there are a lot of other types based on the same process, so they will be suitable for the same task.
 

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It is probably because Neumann used the 2N3819 in a lot of microphones.
By the way: I got a batch of 2N3819 FETs from ebay, there is even an 'F' on the FET (Fairchild?).
They came from China...
Fake or not fake, they are excellent! Can be biased correctly and produce very little noise. (Lower noise  than other brands.)
So not every Chinese seller is selling fake products!
 
RuudNL said:
It is probably because Neumann used the 2N3819 in a lot of microphones.
By the way: I got a batch of 2N3819 FETs from ebay, there is even an 'F' on the FET (Fairchild?).
They came from China...
Fake or not fake, they are excellent! Can be biased correctly and produce very little noise. (Lower noise  than other brands.)
So not every Chinese seller is selling fake products!

Post pic please.
 
RuudNL said:
It is probably because Neumann used the 2N3819 in a lot of microphones.
By the way: I got a batch of 2N3819 FETs from ebay, there is even an 'F' on the FET (Fairchild?).
They came from China...
Fake or not fake, they are excellent! Can be biased correctly and produce very little noise. (Lower noise  than other brands.)
So not every Chinese seller is selling fake products!

Bingo!  I’m building a u87 and u47fet and need transistors.  Didnt want to or need to reinvent the wheel, just wondering what is confirmed to work well in these circuits
 
Maybe i'm the "heathen" here, but i'm 95% sure they didn't pick that particular part number because it was "magical" in any way.
It's much more likely (imho) that there wasn't all that much to choose from at the time, in the first place ;D But what do i know? ::)

rockinrob86 said:
Bingo!  I’m building a u87 and u47fet and need transistors.  Didnt want to or need to reinvent the wheel, just wondering what is confirmed to work well in these circuits
 
Khron said:
Maybe i'm the "heathen" here, but i'm 95% sure they didn't pick that particular part number because it was "magical" in any way.
It's much more likely (imho) that there wasn't all that much to choose from at the time, in the first place ;D But what do i know? ::)

I agree. In those days there were not many FETs to choose from. The 2N3819 was ubiquitous but by no means ideal.

Cheers

Ian
 
RuudNL said:
It is probably because Neumann used the 2N3819 in a lot of microphones.
By the way: I got a batch of 2N3819 FETs from ebay, there is even an 'F' on the FET (Fairchild?).
They came from China...
Fake or not fake, they are excellent! Can be biased correctly and produce very little noise. (Lower noise  than other brands.)
So not every Chinese seller is selling fake products!
Might also be that it's what's usually called for in the BOM of a lot of DIY projects that were written up before the 2N3819 became special order. So you see it on the list and think it's what you need to use.
 
Is the J305 a direct substitution in these Neumann clones?

How can I research replacements better?  I don't mind looking for one, but it seems like others have had to go through this recently as well
 
The J305s work well and sound great.  I have KM84 clones with the J305s and they are go-to mics

Linear Systems is making new boutique FETs and they are excellent; pricey, but worth it in that you know you are getting something that meets the spec.  They make a J305 ,the 2SK170 family (if you like those in microphones), 2N4416, among others.    I find eBay a crap shoot for rare parts—you never know if you are getting the real deal as things go EOL. .

—Mark
 
Is there a way to check if a 2n3819 is real?

My semiconductor analyser tells me its an N Channel JFET but cannot identify drain and source.
 

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