2SK30 substitute for OC-2?

Started by Taylor, March 01, 2010, 02:56:12 AM

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Taylor

What would be an available substitute for the 2SK30 JFET in this circuit?

http://www.aronnelson.com/gallery/main.php/v/Processaurus/OC_2_chopped.gif.html

Or at least: what are the important characteristics for it to do its job right?

cpm

looks like its shunting to vref. It also looks easy to substitute for other transistos, due to that source goes to Vref, and you can pull the gate voltage down to gnd (FET increases Rds when Vgate is lower than Vsource minus some Vgs-off characteristic of each FET), you have ~4v to play with

my guess is whatever FET with a fair Vgs-off up to 3 is a safe bet. Which is easy to find in the usual suspects: J201, BF245, MPF102, 2N5457, etc

NOTE that i tell you all this quite loosely, i'm not an expert at all  8)

2SK30 are the usual FET on boss bypass, it works really well with its very low Rds-on, and high cut off, so probably they just used this model for that Q8 because of availability and convenience




cpm

Quote from: cpm on March 01, 2010, 04:42:28 AM
looks like its shunting to vref. It also looks easy to substitute for other transistos, due to that source goes to Vref, and you can pull the gate voltage down to gnd (FET increases Rds when Vgate is lower than Vsource minus some Vgs-off characteristic of each FET), you have ~4v to play with (and you may change the 1M divider ratio too)

my guess is whatever FET with a fair Vgs-off up to 3 is a safe bet. Which is easy to find in the usual suspects: J201, BF245, MPF102, 2N5457, etc

NOTE that i tell you all this quite loosely, i'm not an expert at all  8)

2SK30 are the usual FET on boss bypass, it works really well with its very low Rds-on, and high cut off, so probably they just used this model for that Q8 because of availability and convenience





oldrocker

#3
I used a 5952 in mine.  I also removed C5 .0022 cap.  It made in sound cleaner (better) to my ears.  But that's up to you.  I would like to hear your opinion on the removal of C5 if you try it.  No one else has tried that yet as far as I know.

isildur100

I used a J201 in mine without any issues.

Taylor