I'm exploring JFETs at the moment; I'd like to use them as a variable resistor and set the resistance with a control voltage. I'm using it to control a 1Vpp sine wave through ds. I'm using a J201 JFET.
What I am interested in: How to calculate the resistance of Rds with Vgs = 0 and Vgs = Vgs(off).
I read this (amongst a lot of other sites and vids) https://effectpedalkits.com/blog/electronics-tutorials-the-jfet-junction-field-effect-transistor-ii-circuit-analysis/
Based on this source, I know that when Vgs = 0, Id = Idss and Vp is fixed (1.5v for a J201) So the equation would be relatively easy:
Rmin= 1/slope = 1/(Idss/Vp) = 1/(0.005/1.5) = 1/0.008333 = 300 ohm
Question: Are my assumptions correct? And how do I calculate the resistance of the JFET when Vgs = Vgs(off). (Do I take Igss from the datasheet for Id then with the corresponding V? This gives me a 20000Million ohm R..)