IIRC Interdigitation? I'm sure I've seen that in power transistors to get low Re.
But my memory is c**p these days ....
The seller asked me for my preferred IDSS of the pairs, I opted for around 10mA, though I can still change my mind.
OK entirely OT. My high school chem instructor mixed up a batch of Aqua regia (King of the solvents, a very strong acid) which he kept on the bench at the front of the classroom. It looked like a mild ferric chloride solution to me. So the next day I swapped his beaker of it for one of ferric chloride. While he was watching I dropped a piece of aluminum foil into the beaker. As expected it was a reasonable nice and foamy reaction. The I stuck my fingers into the beaker to take out the foil. The instructor ran towards me in a panic shouting! He figured out something was up when I started laughing and clearly had no burns. He put the Aqua Regia away in a safe place.
> So they don't do that just with MOSFETs?
http://users.ece.gatech.edu/~lanterma/sdiy/datasheets/transistors/AN-222.pdf
http://users.ece.gatech.edu/~lanterma/sdiy/datasheets/transistors/AN-222.pdf
The ones I got were makred BL and had idss of 17 and 18 ma which is the high end of the V range
I talked with that person and I trust him. He is chief software engineer in a company.
The fake 2SJ74 BL wouldn't pair with 2SK170 BL, he offers matched pairs.
FT1551/FT2551 complementaries, 20W Pd.
As in the Accuphase C-220 from 1977, only preamp with identical devices at the compl. diff. phono input and line stage output, see piccy.
Production of the C-220 seized in 1980, as manufacture of the FT's stopped.
Just the phono stage was the C-7, from '79, kept on going till '84, which suggests that the Accu-P boys were taken by surprise.
http://www.accuphase.com/cat/c-7en.pdf
Look Ma, 100 in an emitter circle.
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99.99% fakes. I have had them sent from diyers, bought from many resources. All fakes. Very high noise, and high distortion. But I am not going to measure further samples for other diyers 🙂
Don't lose faith, Joshua. My colleagues have had better luck, than 99.9%. Just make sure that you know where the seller is located, so that you can make a 'personal' visit, if they are fakes. Still, Parasound, for example, has been 'burned' badly on occasion.
Thanks, John.
It will be a local pickup, no shipment.
I can choose the IDSS group of the 2SK170 / 2SJ74 matched pairs. I opted for about 10mA IDSS, though I can get lower IDSS.
The seller tolled me that he has high quantity of faked ones, which he isn't selling. He makes his living from being a software engineer, not from selling FETs. He is an audio DIY'er, which is why he purchased big quantities of JFETs, he built dome of Borbely designs.
It appears to me that several opportunities to buy discontinued jfets are now available here, on this website. The problem seems to be when someone expects a 'bargain' from the purchase of a now, hard to get, part.
It reminds me of police 'stings' in the USA, and perhaps elsewhere. The police offer: 'a deal you can't refuse', let's say with a bulk drug purchase, and the people who can't miss out on a 'bargain', get arrested, and nothing more.
These jfet fakes seem to be sold to people seeking a 'bargain' compared to the 'going price' of the parts from real suppliers. Buyers, and 'middle men' should beware of too good of a price for these 'getting to be rare' items.
Now, in the end, there will be 2SJ74's produced in quantity. I have seen them, and use them in some of my designs, but they are not readily available yet. They work essentially the same as the original Toshiba. Let's hope they are released openly, soon.
It reminds me of police 'stings' in the USA, and perhaps elsewhere. The police offer: 'a deal you can't refuse', let's say with a bulk drug purchase, and the people who can't miss out on a 'bargain', get arrested, and nothing more.
These jfet fakes seem to be sold to people seeking a 'bargain' compared to the 'going price' of the parts from real suppliers. Buyers, and 'middle men' should beware of too good of a price for these 'getting to be rare' items.
Now, in the end, there will be 2SJ74's produced in quantity. I have seen them, and use them in some of my designs, but they are not readily available yet. They work essentially the same as the original Toshiba. Let's hope they are released openly, soon.
At Charles Hansen's suggestion on this thread, I have purchased a copy of 'Analog Circuit Design' by D. Feucht
I find it next best to 'The Art of Electronics' in its coverage, and more specific solutions for experienced designers, than most textbooks, as well as being derived from real designs, and not just theoretical ones. Highly recommended to those who can afford it.
I find it next best to 'The Art of Electronics' in its coverage, and more specific solutions for experienced designers, than most textbooks, as well as being derived from real designs, and not just theoretical ones. Highly recommended to those who can afford it.
John I'm sure you enjoy it, very good on analog design. Did you buy a printed copy or the CD version?
jan didden
That must have cost you an arm and a leg! But worth it.
BTW, Cyril Bateman has commented on Ed Simon's article in Linear Audio Vol 1 about resistor non-linearity. Cyril has provided copies of test equipment data and app notes, including the CLT1 that Demian uses. I'm sure you're interested in these vintage documents. Here are Cyril's comments with the links to these docs.
jan didden
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