YAJQ (Yet Another JFET Question) - What is happening with through-hole JFETs

[boogietone]

A quick perusal of mouser and digikey shows that many through-hole JFETs, both N and P channel, devices are listed as Obsolete/End of Life. Not being familiar with electronic component life cycles, I ask is this just a normal turn over event or is the beginning of the end for the through-hole components?

[DavenPaget]

A quick perusal of mouser and digikey shows that many through-hole JFETs, both N and P channel, devices are listed as Obsolete/End of Life. Not being familiar with electronic component life cycles, I ask is this just a normal turn over event or is the beginning of the end for the through-hole components?

Why not check Newark/Farnell ?

[boogietone]

Newark does show stock and does not indicate end of life (EOL) status. But, they do not seem to indicate this status for any components. Farnell is "Site indisponible."

Mouser shows decent stock on some of the devices as well even though they are EOL.

Nonetheless, the 2SK30A that Mark Hammer is asking about in the other thread is not available anywhere I looked and it's replacement (as per Newark), the NTE458, is "NRND: Not recommended for new designs" according to Mouser.

And, a search of Mouser and Digikey for 2N5485 turns up 16 total catalog entries of which all but 1 is both available and not "End Of Life."

Just being curious before I commit to designing with one of these. It would be hard to understand that these are completely disappearing. I suspect that another company is picking up production or that Fairchild is going to reissue them differently.

[R.G.]

The beginning of the end of the through-hole component started some time ago. There may be a long twilight, as vacuum tubes have had, but they're fading and have been.

It's dollars and cents. Us hobby types are very much like little inconsequential warts on the electronics components world. We don't have the volume in a hear of DIY in this forum that one production run of one pedal for Boss does.

The twilight will be long. As witness - there are still companies making germanium transistors today. In fact, I do know of places that sell **buggywhips**. It'll just get harder to find.

[kwijibo]

I think we'll be better off than with a vacuum tube transition - the parts will still be made, just not in the most convenient packages. If DIYers decide they want to resist using SMD parts then I would not be surprised if some enterprising person starts selling them with pre-soldered adapters.

[R.G.]

Already happening. Small Bear.

[Electron Tornado]

Just trying to get some perspective on this. I don't know the timeline, or the rate of change, so to speak, but the use of tubes went into decline, faster in some places than in others. You also stopped seeing tube testers in electronics shops. Then, tubes started making a bit of a comeback in the 80s or 90s, though that may have only been for higher end audio.

While economics drive the use of surface mount components, do through hole components offer any advantages that would cause them to remain in use, or eventually influence people to return to using them more?

Another good question - who is using germanium transistors to the extent that it would make it economically viable to continue to produce them? Come to think of it, have manufacturing processes been improved for germanium that new builds are better quality?

[R.G.]

While economics drive the use of surface mount components, do through hole components offer any advantages that would cause them to remain in use, or eventually influence people to return to using them more?

Solely prototyping ease. Well, OK, cork-sniffing.    There is already a contingent that thinks that through hole components sound better, even if they are the same silicon chip in a different package. You'll start seeing adverts saying "all through-hole components; none of that ugly-sounding SMD stuff".  In a world where there are people who can sell power and speaker cables for thousands of dollars (that's not a typing mistake, BTW), nothing is immune from the cork sniffing crowd.

Another good question - who is using germanium transistors to the extent that it would make it economically viable to continue to produce them?

Military replacement/repair.

Come to think of it, have manufacturing processes been improved for germanium that new builds are better quality?

Yes. They are of better "quality" in the datasheet sense, so they have higher gain and lower leakage, lower noise, etc. That usually means that they don't have the quirky oddities that are coveted by the imperfect old ones as well, as the imperfections sought for guitar effects are most assuredly not on datasheets.

[smallbearelec]

A quick perusal of mouser and digikey shows that many through-hole JFETs, both N and P channel, devices are listed as Obsolete/End of Life.

I, also, ran into this when I went shopping recently. The 2N5457, for example, is due for "last buy" status in February.

All of the FET types that I presently list will be available for next few years, at least, because I am/will be investing in stock. Once a part goes obsolete, my no wholesale/right-to-limit-quantity policy will apply. Many through-hole parts will continue to be available for a long time yet from some of the brokerages that I deal with, though they will necessarily be more expensive.

Regards
SD

[amptramp]

Just trying to get some perspective on this. I don't know the timeline, or the rate of change, so to speak, but the use of tubes went into decline, faster in some places than in others. You also stopped seeing tube testers in electronics shops. Then, tubes started making a bit of a comeback in the 80s or 90s, though that may have only been for higher end audio.

Tubes are coveted in high-end audio and guitar amps for a reason - they offer linearity and the ability to get pleasant-sounding distortion.  Indeed, there are very expensive single-ended triode amps which I have heard that have obvious distortion (>3%), and although you can hear the difference from an amplifier with lower distortion, it still sounds good.

While economics drive the use of surface mount components, do through hole components offer any advantages that would cause them to remain in use, or eventually influence people to return to using them more?

Through-hole offers one advantage - you can flex the circuit board and parts don't fly off.  Some of you may consider your stompboxes to be your children, but all your children are going to be abused.  They will be tossed into vans, manhandled into position on a stage, transported in freezing cold and blazing heat and yanked around by their cables for most of their life.  For surface mount to work, it takes a very stiff board with a temperature coefficient of expansion matched to the parts to survive - either that or an elastomer board where the board is so soft, you cannot stress the connections by flexing the board.

The advantage of surface-mount is that there are no holes to drill in the board.  Holes are expensive because epoxy-glass destroys drills easily and the process has to be stopped frequently to change drills.

Another good question - who is using germanium transistors to the extent that it would make it economically viable to continue to produce them? Come to think of it, have manufacturing processes been improved for germanium that new builds are better quality?

Fabrication technology has improved since the heyday of germanium, but no one seems to want to overcome the main difficulty with germanium - high leakage due to the fact that germanium oxide is conductive.  Where silicon benefits from a layer of SiO₂ which is basically quartz, a non-conductor, no one seems to be looking for something similar for germanium.  The projected volume simply doesn't warrant that much research.

[PRR]

> no one seems to be looking for something similar for germanium.

If there were a practical fix, it would have been found by now; probably before 1970.

I don't think it is just the Germanium Oxide thing though. Ge just conducts too well.

"Obsolete/End of Life".... the whole deal about ICs is that a million dollar chip can cost a buck each if you make a million of them. Most devices run 100,000 units produced and some have run hundreds of millions. Then just like buggy-whips, demand falls off as newer/better devices are introduced and accepted. The bean-counters watch the trends. They have a pretty good idea when the market will fall to zero, and how many will be sold in the last year or three.

Chips/transistors are not produced steady like cars. They make 10,000 or 100.000 of one part, then convert to another part and make a bunch of that.

When they predict that the total remaining demand is about 10,000 parts, they issue the "Obsolete/End of Life" alert. Sometimes the word is "lifetime buy". That literally means "buy all the parts you will EVER need NOW". If you have 40 old bombers that need 2 of that device every year and you fear you may be flying it for another 10 years, you immediately place an order for 40*2*10 or a thousand of the "lifetime buy" parts.

Most large-volume users already migrated away from "obsolete" parts; that's why demand declined. At the top of the tail you have small-volume production. These guys may lifetime-buy; but often it is cheaper/safer to re-design for a still-common part. Next you have large repair operations. Military is a classic demand for "obsolete" parts. But occasionally we do retire old warbird systems, or adapt something from a newer warbird, and there's enough military systems in service to be worth figuring-out a near-enough part and the re-calibration manual.

The DIY market is the flea on the end of the hair on the tail. Nobody who can make a million parts is going to do a run of 100 for SmallBear's annual sales-volume. Heck, Ford won't even keep the Crown Vic in production for the few thousand police and towncar buyers.

[diagrammatiks]

The only good thing is that now a lot of ... I guess hobbyist centric builders are designing and releasing smd convertor boards for the popular formats.

I know that they have sop, sot23, soic boards out now.