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Part Sourcing Assistance/Advice Thread


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6 hours ago, kevin gilmore said:

suitable replacements seem to be 2sa1552 / 2sc4027

toshiba tta004b / ttc004b also look compatible

I bought a bunch of tta004b/ttc004b for this exact purpose but have not tried them yet. 

Would be nice if we can find something that's also pin-compatible with 2SK216/2SJ79.

Edited by mwl168
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On 2/26/2021 at 8:39 AM, jamesmking said:

quick heads up KSA1220AYS transistors are now END OF LIFE 



mouser is currently out of stock

radio spares has stock

farnell is out

digikey is out


That is just part of OnSemi's quest to obsolete anything remotely of use to audio. They took over Fairchild and Sanyo and have systematically removed many much loved discrete transistors from both their lines. I hate OnSemi with a passion. A big fucking hatred. A big fucking passionate hatred.

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It isn't confined to On-Semi. Rohm did the same thing with all their low noise offerings ages ago, So did Renesas with the J79/K216 - in fact lateral MOSFETs are a thing of the past. Most p-channel jFETs have gone, and many low-noise jFETs of any flavour. The latest to go is the very low noise J107 (another On-Semi casualty). NXP killed off the n-jFET BF862 (lower noise than the K170) and indeed all jFETs, period. Analog Devices has just EOL'd the monolithic dual MAT01, unusual because it BVceo is 45V; every other low-noise dual is 40V. So in one of my applications where the maximum Vce is 41V it is the only part that will do.

Hell On-Semi even obsoleted that ubiquitous BC560! OK they still make the SM version, the BC860, but it is tough nuts if you needed the power dissipation of a discrete part.

If a part does not go in an automotive, mobile device, TV or other ultra-high volume application, semiconductor manufacturers lose interest real fast.

The glimmers of hope are Toshiba, Diodes Inc, Linear Systems and THAT. And LS is the only one with a credible line up of single and dual jFETs and dual bipolars in multiple package choice.

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The other one I forgot to mention if you have deep pockets is Interfet. They do have possibly the lowest noise n-JFET ever, the IF3601/3602. These have wild and unpredictable Idss, but a noise voltage of typically 0.3nV/rootHz and a noise corner of a few Hz. If you can bear that $100 price tag for the dual version and $30 for the single.

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Besides, there are also companies that close or go bankrupt... I have several grains of sand from Semisouth designed for use in solar panels/conversors AC/DC (and later on amplifiers obviously 😉) that today cost a small fortune.

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  • 2 weeks later...


I just about to finish a Dynalo Mini and strugglig with the input fets. I did read a lot back this thread and I see what is obsolete etc., but I can not find what I can order. I know on ebay there are unknown sellers selling these, but if you guys have a suggestion I can get from Mouser / Farnell / similar, that would be great.

I've looked these so far:

2SC3381 2SA1349
2SK389 2SJ109
LSK489 LSJ689
2SK170 2SJ74

Thanks a lot!!

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The only ones in your list currently available (without contortions) are the Linear Systems LSK489 / LSJ689. These are available from Trendsetter in the US. I'm not sure who in Europe carries them. You didn't indicate where you are, but judging by the Farnell I assumed Europe.

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For Europe and for the 489/689, I was referred by Linear to: 



Phone:+ 49-7533-949-8760

Fax:+ 49-7533-949-8762

Email:[email protected]


which turned out to be very close to a one man operation :)

However, they didn't sell the 689 to private customers at the time (two years ago), so I had to use a company address to get those. 

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I've bought quite a few Linear Systems single and dual JFETs from Micross. The pain in the ass is that you have to complete and end-user form now for every damned order. It didn't used to be the case, but must relate to some change in US export rules, possibly during the administration of the orange menace.

Mind you it is not as onerous as importing potentially sensitive semiconductors covered by ITAR (International Traffic in Arms Regulations), which many space qualified semiconductors are. You have to sign documents that say you will go to jail if you sell them on, or even lose them. They need to be stored in a locked location, a register of use kept and signed, and any devices you don't use must be destroyed or returned. Fortunately launching into space qualifies as "destroyed"!

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  • 3 weeks later...

To me this looks like a small pressure pad but to Digikey, Ebay, Amazon and the rest of the internet it is something else. There is no manufacturer name or part number so that is a dead end. Can anyone name this part or guide me as to where I can find a replacement.


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Is there any easy way to invert (“convert from positive to negative”) a gerber file. I want to invert the solder paste gerber file – then I think I can make a CNC file and mill PCB  stencils.

Or at least I can try…

Edited by JoaMat
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