madbeanpedals::forum

General => Open Discussion => Topic started by: Mattallica on March 26, 2016, 04:14:18 AM

Title: JFET J309 Equivalent
Post by: Mattallica on March 26, 2016, 04:14:18 AM
Anyone know what a good equivalent to a J309 JFET is? I can't find the part in any Eagle library, and I was curious anyway as they seem to be *slightly* more difficult to obtain than your average transistor. Thanks!
Title: Re: JFET J309 Equivalent
Post by: EBRAddict on March 26, 2016, 11:54:37 AM
Mouser has them $4 each lol

If you look at the datasheet parameters of Vgs(off) aka Vp aka Vth it is -1V to -4V and Idss is 12-30mA.

If it is used as a buffer (source follower) it should be easy to replace with something else. Otherwise find another part with working, semi-matching parameters or rejigger the schematic to supply a useable Vgs and deal with a different current level.

Or just pay the $4
Title: Re: JFET J309 Equivalent
Post by: Haberdasher on March 26, 2016, 01:59:47 PM
For the eagle aspect, just pick another fet with the same pinout, and then you can always rename it J309 if you want to.  Schematics are dumb, they don't care.
Title: Re: JFET J309 Equivalent
Post by: gtr2 on March 26, 2016, 02:04:58 PM
Quote from: Haberdasher on March 26, 2016, 01:59:47 PM
Schematics are dumb, they don't care.

Hey, my schematics take offense to that statement ;)