Choosing JFET for bypass switching

[m4268588]

[mark2]

Thanks for the clarification on the TS, and what happens if it's not biased on both the S&D.

And for the extra info Rob. I'll check those threads out now.

I'm going to be trying out some 2SK208-R for switching by the way. It seems to have a similar VGS(off) as other commonly used JFETs: −0.4 to −5.0V.

[m4268588]

Vf=0.3 to 0.4V(lower)

[mark2]

Vf=0.3 to 0.4V(lower)

I'll spend some more time trying to understand, but can you explain a little more about what you're trying to point out? Thanks!

[m4268588]

Because there is small current flowing to the diode.
It is good to make a large estimate for safety reasons.

[mark2]

Large CV? My plan is to use a uC and MOSFET to drive 9V to turn on the JFET, if that's what you mean.

[m4268588]

Turns "ON" at CV=9V.
Use J-FET with small Vgs as possible.