Hacker News new | ask | show | jobs
by klodolph 1839 days ago
Yes, I built a guitar pedal that was designed around JFET gain stages and the JFETs had to be sourced from a specialist. I wonder if they're still being made. Most of the discrete JFETs I see available are for switching applications.
3 comments

Low noise JFETS are hard to find today. Devices like the Toshiba 2SK369, 2SK117, 2SK170 etc. went out of production years ago for being mostly THT and possibly non ROHS devices, while purely functionally speaking they would still be great parts. They can be seen online on Ebay, Aliexpress, etc. but those are almost always relabeled fakes; real ones are hard to find and not cheap. Before learning about counterfeit components the hard way, I bought two bags of 2SK117 from two vendors on Ebay: they were identical, but when fit in a circuit, I had to recalculate the drain and source resistor with all the parts from one vendor because it clearly had different specs than a real 2SK117. Ugh! ...lesson learned. Somebody suggested the use of the BF256 JFET in audio circuits, even in RIAA phono cartridge preamps. It is a RF part (the natural successor and direct equivalent of the venerable BF245) but it seems it is also a low noise part capable of working down to audio with no issues. It went out of production more recently than other models and some vendors still have stocks available. Probably not as quiet as the others though.
I bought 4000 J201’s when I saw they were becoming obsolete, I still have most of them. But, I think there are better choices out there anyhow, that’s just what I’m used to using. They’re really easy to bias.
Linear Systems still makes JFETs and all sorts of other discrete parts that everyone else stopped making.