Why no H11F1 OptoFET?

[Lostgallifreyan]

The H11F1 is (was) multisourced, Fairchild, Isocom, and possibly others.
I bought 20 from Digikey only a few weeks ago. Now they have none in stock,
and a recent poster here says he got a mail from Digikey announcing that
Fairchild will stop making them (not that they ever did, they bought out
the maker QT Optoelectronics, and now seem determined to bury this part).
RS Components list them for sale, made by Isocom, but on Isocom's site that
part and also H11F2 and H11F3 optoFET's have vanished with no trace that
they ever made any.

Despite recent changes to make them RoHS compliant, suggesting that full
production was intended to continue, this optoFET seems to be vanishing the
way of the Norwegian Blue. Anyone know why? If a component is good enough
that more than one company wants to make them, how is it that they can all
vanish as if some weird and surprisingly effective conspiracy was shutting
them all down at once? I'd like to know what could account for it, and what
could be used instead.

Most of all, I must know why and how such a thing can happen. It doesn't
make sense to specify any but the most enduring and commonplace parts in a
design if something as established as this can be torn down in a week or
three without notice. I've seen several people here complain of this kind
of thing, and it seems to be getting worse.

 

[[email protected]]

The H11F1is (was) multisourced, Fairchild, Isocom, and possibly others.
I bought 20 from Digikey only a few weeks ago. Now they have none in stock,
and a recent poster here says he got a mail from Digikey announcing that
Fairchild will stop making them (not that they ever did, they bought out
the maker QT Optoelectronics, and now seem determined to bury this part).
RS Components list them for sale, made by Isocom, but on Isocom's site that
part and also H11F2 and H11F3 optoFET's have vanished with no trace that
they ever made any.

Despite recent changes to make them RoHS compliant, suggesting that full
production was intended to continue, this optoFET seems to be vanishing the
way of the Norwegian Blue. Anyone know why? If a component is good enough
that more than one company wants to make them, how is it that they can all
vanish as if some weird and surprisingly effective conspiracy was shutting
them all down at once? I'd like to know what could account for it, and what
could be used instead.

Most of all, I must know why and how such a thing can happen. It doesn't
make sense to specify any but the most enduring and commonplace parts in a
design if something as established as this can be torn down in a week or
three without notice. I've seen several people here complain of this kind
of thing, and it seems to be getting worse.

NTE lists a crossover of NTE3085... Web-tronics.com shows them in
stock, as well as weisd.com. Tried plugging it into Digikey with no
avail. Mouser shows in-stock with their part number 526-NTE3085.

Hope this helps.

-Gordon

 

[Eeyore]

The H11F1 is (was) multisourced, Fairchild, Isocom, and possibly others.
I bought 20 from Digikey only a few weeks ago. Now they have none in stock

Farnell has some.
http://uk.farnell.com/jsp/search/browse.jsp?N=411&Ntk=gensearch_001&Ntt=h11f1&Ntx=&_requestid=111596

Graham

 

[Lostgallifreyan]

NTE lists a crossover of NTE3085... Web-tronics.com shows them in
stock, as well as weisd.com. Tried plugging it into Digikey with no
avail. Mouser shows in-stock with their part number 526-NTE3085.

Hope this helps.

Thankyou. It does, a lot. As these IC's are expensive, (even H11F1's are in
UK, the last were bought via a friend in the US), I'll only buy a few as I
need them so I need to know I can get them again. If I can, I can get by.
What's scary is the thought that something as useful as a FET optoisolator
could vanish as if suddenly no-one thinks they are useful. Google shows
many inventive uses for them, but if the makers decide they don't value any
of that, it helps to know why they should not do so. I can't see how
something with such a unique and powerful function could be replaced or
made obsolete.

 

[Lostgallifreyan]

Farnell has some.
http://uk.farnell.com/jsp/search/browse.jsp?N=411&Ntk=gensearch_001&Ntt
=h11f1&Ntx=&_requestid=111596

Graham

So do RS. But for how long? I'm not thinking about the few drying pools
left, I can raid a couple of those if I need (and I will, as the NTE3085
that Gordon posted about costs at least double). I didn't raise a new
thread to find a handful, but to question what looks like the end of the
line for something that showed every indication of being new. It reminds me
of a news story about a village that grew daffodils for a show, and whose
occupants woke one morning to find someone had cut all the buds off during
the night. This obviously isn't the dying end of an old product no-one
needs anymore, so what's going on?

 

[[email protected]]

Thankyou. It does, a lot. As these IC's are expensive, (even H11F1's are in
UK, the last were bought via a friend in the US), I'll only buy a few as I
need them so I need to know I can get them again. If I can, I can get by.
What's scary is the thought that something as useful as a FET optoisolator
could vanish as if suddenly no-one thinks they are useful. Google shows
many inventive uses for them, but if the makers decide they don't value any
of that, it helps to know why they should not do so. I can't see how
something with such a unique and powerful function could be replaced or
made obsolete.

It concerns me as well... but that's the way of the world anymore. I
remember a time when you could get pretty much anything you wanted at
RadioShack... but the RadioShack of today is nothing like what it was
ten years ago. Used to be once upon a time that people were excited
about this hobby, and you saw all sorts of incredible and inventive
things being done. All of that's gone now. The beancounters have
taken over. Electronics isn't sexy anymore.... so if some large
corporation isn't buying them by the tens of millions... the profit
margins are too low to even bother with catering to a virtually
nonexistent hobbyist market.

Expect to see lots of handy things disappear as time goes on... and as
modern manufacturing moves more and more toward SOICs and ASICs...
expect to see our hobby relegated to the complete, utter fringes of
society.

Glad I could be of help.

-Gordon

 

[Eeyore]

Thankyou. It does, a lot. As these IC's are expensive, (even H11F1's are in
UK, the last were bought via a friend in the US), I'll only buy a few as I
need them so I need to know I can get them again. If I can, I can get by.
What's scary is the thought that something as useful as a FET optoisolator
could vanish as if suddenly no-one thinks they are useful. Google shows
many inventive uses for them,

But are they sensible uses ?

but if the makers decide they don't value any
of that, it helps to know why they should not do so. I can't see how
something with such a unique and powerful function could be replaced or
made obsolete.

If its possible to do it with a cheaper part you can be sure that's what will
happen. No demand for the part and it'll be discontinued.

The days of designers using boutique parts have vanished mainly. What
application are you using them in ?

Graham

 

[Lostgallifreyan]

But are they sensible uses ?

Yes. Go look at the H11F1 datasheet, that alone shows some uses that make
them worth saving.

Your talk of 'boutique' parts in this case is stupid. If you beleive that
logic you'll soon be advocating the censure of mere fripperies like the
thyristor and the triac.

You shouldn't need to know my application to justify the need to retain
such a part, and I shouldn;t have to tell you. What do you seek to do? Ask
me to puty it up su you can knock it down? The makers didn't need your
justification to make the part in the first place, so why does your
judgement now depend on mine? For your curiosity, I will answer: a laser
diode modulator. And don't tell me there is an easier or cheaper way to get
a shunt modulator that has excellent isolation and linearity than this,
because there isn't one. An optoFET is the only way to do that cheaply with
a very low parts count. I've seen other designs in lots of commercial
designs, and most of them are horrible. In their effots to be cheap they've
reduced all the safety and linearity they want to brag about, and one
little optoFET could have made a LOT of difference.

 

[Lostgallifreyan]

Expect to see lots of handy things disappear as time goes on... and as
modern manufacturing moves more and more toward SOICs and ASICs...
expect to see our hobby relegated to the complete, utter fringes of
society.

Eloi and Morlocks. > This wouldn't be the first time I've been reminded
of those. Wells was right.

 

[Eeyore]

Eeyore wrote


Yes. Go look at the H11F1 datasheet,

Whose ?

that alone shows some uses that make them worth saving.

I was hoping you'd say which ones were sensible in your assessment.

Your talk of 'boutique' parts in this case is stupid. If you beleive that
logic you'll soon be advocating the censure of mere fripperies like the
thyristor and the triac.

Hardly. They're used by the bucketful.

You shouldn't need to know my application to justify the need to retain
such a part, and I shouldn;t have to tell you. What do you seek to do?

Because I'm curious why you need it and maybe I could have offered another
solution.

Ask me to puty it up su you can knock it down? The makers didn't need your
justification to make the part in the first place, so why does your judgement
now depend on mine?

You're getting a bit pissy over a simple question here. If you don't want to
tell me, that's fine.

Graham

 

[Lostgallifreyan]

Whose ?

Whose do you think? Did you read any previous posts on this, or did you
drily insert your arid scholarly wit in the assumption that you know FAR
too much to actually read a post before answering it?

FAIRCHILD. That would be a good start.

I was hoping you'd say which ones were sensible in your assessment.

What is this, a masterclass?? Try the sample/hold with very low leakage and
no feedback to the controlling system, or the noiseless AGC/switch/fader
for audio, or the isolated laser diode modulator.

Hardly. They're used by the bucketful.



Because I'm curious why you need it and maybe I could have offered
another solution.



You're getting a bit pissy over a simple question here. If you don't
want to tell me, that's fine.

No, I'm getting pissy over your dry aura of scholasticism that has no
grounds for its high and mighty airs. And I did tell you. I guess you
didn't read that either.

 

[Lostgallifreyan]

Because I'm curious why you need it and maybe I could have offered
another solution.

Not interested. I'm not so blind I can't see alternatives, or that your
offer is really based on your desire to show that I'm wrong. Don't bother.
If you want to impress, show why the makers of that IC, Isocom, Fairchild,
and the form NTE that have emulated it and justify more than double the
cost see fit to make them in the first place. If you can show why all those
people are wrong, I'll be mightily impressed, believe me.

 

[Eeyore]

Eeyore wrote

Whose do you think?

I was asking you. You didn't specify and I don't believe in making guesses. How
about specifying which uses you think are uniquely suitable to opto-fets ?

Graham

 

[Eeyore]

What is this, a masterclass??

It could very easily be.

Try the sample/hold with very low leakage

I have no application for that. The absence of charge injection is cute but
everything else could be done in any pratical application I can think of with
simple level shifting.

and no feedback to the controlling system, or the noiseless AGC/switch/fader
for audio,

It's fairly rubbish for audio. More than about 75mV rms across the fet and you
get distortion. VCAs do much better and for ages I've also been using
opto-coupled resistors. These are vey nice and a lot cheaper (as little as 20
cents in China) and even match quite well.

Graham

 

[Eeyore]

Eeyore wrote

No, I'm getting pissy over your dry aura of scholasticism

More like practical real world low-cost design experience. I DO NOT use silly
frivolous pricey boutique parts.

You remind me of the guys (so-called designers) who would get all excited over
RS introducing some new exotic expensive part into their catalogue who then felt
obliged to design it in to their employer's products and design the company into
financial failure.

Graham

 

[Eeyore]

Eeyore wrote

Not interested. I'm not so blind I can't see alternatives, or that your
offer is really based on your desire to show that I'm wrong. Don't bother.
If you want to impress, show why the makers of that IC, Isocom, Fairchild,
and the form NTE that have emulated it and justify more than double the cost

I rather doubt that. They probably picked up some equivalents and just re-marked
them, RS components style.

see fit to make them in the first place.

Because they could ?

If you can show why all those people are wrong, I'll be mightily impressed,
believe me.

Wrong about what ? Once upon a time there was demand and they made a profit.
That's good business. If there's no demand now they'll stop making them. That's
good business sense.

Incidentally, if you look at the applications on the Fairchild data sheet, many
are analog. Much of that is done in DSP now. I can't imagine anyone making a
filter tuned with opto-fets these days when you can do the same thing more
accurately with better THD and noise figures and cheaper too in DSP.

Also, if you must, these optically coupled resistors are about 20 cents....
http://www.sbcds.com.cn/en/Products.asp?Cid=172

Graham

 

[[email protected]]

Not interested. I'm not so blind I can't see alternatives, or that your
offer is really based on your desire to show that I'm wrong. Don't bother.
If you want to impress, show why the makers of that IC, Isocom, Fairchild,
and the form NTE that have emulated it and justify more than double the
cost see fit to make them in the first place. If you can show why all those
people are wrong, I'll be mightily impressed, believe me.

Dude... seriously. Go take a prozac or something. I get the
impression Eeyore is only trying to help.

 

[Lostgallifreyan]

I was asking you. You didn't specify and I don't believe in making
guesses. How about specifying which uses you think are uniquely
suitable to opto-fets ?

Given only two or three firms mentioned, and one that comes up for most
Google results, you didn't have to guess, you had to think.

As for 'unique': unfair question, and you know it. There are often other
ways to do things, the question is which is best. A lot of things justify
this part type, as the makers obviously realised. If a lot of people choose
not to use them, fine, but when you want the resistor-like behaviour of a
FET without the complications of a bipolar type, and the total electrical
isolation that this part offers, an optoFET is the best part to choose.

You're asking the wrong question. Instead of asking me why the part should
exist, ask the makers. All of them. They can answer better than I ever can.
All I ask is that having made them, I'd like to know why they might stop,
having gone through RoHS adjustments in a clear effort to continue, and
what replacements might be found. Gordon chose to help, you chose to argue.
I accepted the invite, but it gets old fast. If I'm to argue further I want
it to be with some better reasoning and attention than you've shown.

 

[Lostgallifreyan]

You remind me of the guys (so-called designers) who would get all
excited over RS introducing some new exotic expensive part into their
catalogue who then felt obliged to design it in to their employer's
products and design the company into financial failure.

Wrong. I try to use basic parts where possible. I just happen to consider
an optoFET as a basic part, just as a bipolar optoisolator is a basic part.
I don't like using new unusual parts with complex or exotic special
functions either, but you can't see that can you? All you can see is
someone who knows less, therefore must know virtually nothing. You're all
judgement, but so inattentive of stuff in the posts you're answering, that
you look more ignorant then you should.

 

[Lostgallifreyan]

Dude... seriously. Go take a prozac or something. I get the
impression Eeyore is only trying to help.

I don't. I felt like arguing with him. Your help was useful. His wasn't.