Any suggestions?
I was under the impression that the 2sk369 was about the best I could get for the purpose.
Magura 🙂
I was under the impression that the 2sk369 was about the best I could get for the purpose.
Magura 🙂
another UnDIY'er thread
Looks like the real problem here is, this thread seems to be one of the "not so DIY Audio" pointers thread, where those with commercial interests and products can probe each others IP, sort of like writing a patent such that the examiner will approve it as having legs, but witholding enough info to truly protect the trade secret that makes it unique (and hopefully profitable).
All those DIY'ers not in the industry posting her, raise your hands...😀😉
Looks like the real problem here is, this thread seems to be one of the "not so DIY Audio" pointers thread, where those with commercial interests and products can probe each others IP, sort of like writing a patent such that the examiner will approve it as having legs, but witholding enough info to truly protect the trade secret that makes it unique (and hopefully profitable).
All those DIY'ers not in the industry posting her, raise your hands...😀😉
out of specification LSK170c with Idss >20mA!!!
I have a few that go to 29mA Idss. As best as I can measure with my methods.
You don't count! As you give useful advice, that actually has value to those of us less experienced
The same goes for Scott, he also can't claim any status in that clan.
Magura 🙂
Well, has everyone had their say? I will now ask a couple of experts, the people who actually design fets, and see what they say.
Unlikely.
They typically have double the 2SK170 transconductance and this can't be only a gaussian tail. Most likely, a larger area chip of the same cell layout.
That's would be real close to a 2sk269, but I bet that the capacitances also is higher than for an average LSK170c?
Magura 🙂
does that rule out lsk170c (in spec) and lsk170c+ (higher than spec Idss) from some or all circuit uses? the c+ is roughly equivalent to 2sk369v.
Which uses would not suit a higher die area, if that is what linear are producing?
Which uses would not suit a higher die area, if that is what linear are producing?
Last edited:
Unfortunately some of these might be equally obsolete, I was thinking of things like the old E410 series from Siliconix which might be available from Linear Systems. The noise gets down to 3nV or so and the C's are only 1-3pF. By linearity I mean gos. The input Vgs-Id transfer function is the same square law for all FET's.
EDIT- Hand matched 2SK222's would give you a good go too. 10mS at 1mA and only 8-10pF.
Last edited:
Andrew, I am certainly glad that you found some 29ma LSK170's. They have a complement, now in the same range. Anyone who got a p channel data sheet at Burning Amp can prove this. It is a new part designation.
Try the Hoya progressive lens. Expensive, but worth every penny. No swimming effect. Closest in similarity to single vision lenses I've ever had.
Any idea how much capacitance vary for different samples of the same device? Also, do you guys use the data sheet values for capacitance or you actually measure the device at hand? If you measure, is the procedure involved?
Don't quite get the drift here, I certainly am not in the audio industry. The non-DIY aspect to me is "if you can't get X unobtainable part there is no point in proceeding".
Well, what I have to say is this: I predict that IF you parallel two 2sk389's with an Idss at 8ma, you will have more input capacitance, that one 2sk389 with an Idss of 16ma. Geometry rules, not Idss. You know, twice the surface area in the device's effective geometry gives more input capacitance. Idss is controlled by another variable, does anyone know what it is?
Apply a square wave via a series resistor. Measure rise time. I'll probably screw the pooch on the constant (away from my references), but I think the capacitance is the time for the square wave leading edge to reach 63% of its max value divided by the series resistance.
First things first. We know that the LSK170 (for example) can have a wide Idss range, even up to 29ma. Why? What is the mechanism for the spread in Idss? It is not geometry, is it? Don't they all look the same under the microscope?
Hmm, they both are about as obsolete as they come. At least the usual suspects didn't have any.
Something tells me that I should just be happy about the stock of 2sk369bl.
Magura 🙂
John, now look, those who knows don't bother playing your little games, those who don't know, also don't bother playing your little games.
So, guess what?
Either explain what you claim to know, or don't, but really, get a hold of yourself.
Nobody bothers playing your little games.
What can I say? It's a damned shame. You're having a bad day.
Magura 🙂
FYI - Data sheets unfortunately use the concept of Ciss and Crss. The extrapolated zero bias capacitances and formula for C vs V (usually ~1/3 power law) is the way SPICE does it and I find this preferable. In this case Cgs and Cgd are usually about the same value. The main point is that you can compute the correct value for each in your circuit.
- Status
- Not open for further replies.