[sdiy] Pet Peeves

Ben Bradley ben.pi.bradley at gmail.com
Sat May 12 07:06:08 CEST 2018


Tonight's Pet Peeve: LTspice isn't updating its database. I'm on the
net, I thought surely Linear Tech's website isn't down ...

Checking linear-tech.com I see it's now Analog, which bought Linear
Tech (I might have heard about this before, but I forgot), they've
moved everything over to the Analog site, so of course it no longer
works.

So I downloaded the latest LTspice from Analog and am now running it.

Less immediately, but recently, my pet peeve is seeing all these
electronics articles and schematics from everywhere in the last
several decades that use components (not JUST the original SSM/CEM
chips, but LOTS of things!) that are no longer made. This isn't the
article authors' fault, nor really the manufacturers (whom I really
want to blame), as they're only responding to trailing sales of older
products (and also, as discussed before, older fabs and processes
being replaced by new ones, and it not being cost effective to update
the parts).

I want to make something with a really high impedance input (not
necessarily synth related), and while I'm familiar with basically how
FETs work, I've rarely used them. I see online schematics more for
inspiration of new designs rather than to recreate an older thing
(hey, that jfet buffer stage does just what I want, but they don't
make that jfet anymore, will any N-channel do there?), and I'd like to
design and make something I could put into production, or at least
write an article on and not have to say "this part is no longer made,
scrounge it wherever you can."

So just now I put down a jfet in LTspice, right-click and select "Pick
New JFET" and I see what, a dozen types? Few if any of these
correspond to jfets on old schematics, and I have to look them up of
Digikey and Mouser to see which ones are still made (I see there's
Central Semiconductor that I've seen before, and now I see InterFet -
they look similar to Rochester Electronics, selling the worlds last
bulk collection of obsoleted parts for many times the original
prices).

Then I put down a MOSFET and pick a new type. There's about a THOUSAND
or so! And that surely can't all be power MOSFETS of various voltage
and current ratings.

Someone didn't tell me or I didn't see That Article in whatever online
electronics magazine (or TAOE 3rd Edition? Should I have bought that
instead of all of Electronotes?) that says "JFETS are GOING AWAY, but
there's plenty of MOSFETS you can use!" I'll leave the remaining JFETs
for the people who do stompboxes and insist on "that original circuit"
with JFETs, germanium BJTs or whatever.



On Sat, May 5, 2018 at 12:38 AM,  <rsdio at audiobanshee.com> wrote:
> We clearly live in an age where companies are designing chips without the level of testing or guarantees that we used to rely upon.
>
> I mean, chips are such a commodity that people are stealing duds and reprinting them with expensive part numbers on them just to scam the market. Is it a stretch to say that putting out a chip without a complete data sheet is somewhere on the same spectrum, a little closer to the fakes?
>
> Brian “How’s that for a Rant” Willoughby
>
>
> On May 4, 2018, at 11:28 AM, MTG <grant at musictechnologiesgroup.com> wrote:
>> I was looking at some SRAM recently and it was a pretty short datasheet. I guess they assume you've read all the earlier ones on the same type of device written by companies that published actual data books.
>>
>> On 5/4/2018 11:17 AM, Tim Ressel wrote:
>>> To be fair it looks like the segment naming is pretty standard. Still it would nice to have it on the sheet.
>>> --tr
>>> On 5/4/2018 11:11 AM, Dave Magnuson wrote:
>>>> Now, how could that *possibly* be important.   Sheesh.
>>>>
>>>> That's a pretty big omission
>>>>
>>>> -----Original Message-----
>>>> From: Tim Ressel
>>>> Sent: Friday, May 4, 2018 1:55 PM
>>>>
>>>> Who's up for a Friday rant?
>>>>
>>>> My pet peeve this morning: incomplete data sheets. I'm looking at the
>>>> Lite-On LTP-3862 and nowhere does it relate the segment names on the pins to
>>>> the segments on the display.
>
>
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