> Sounds interesting. Neither Fairchild or National have data on the 2N5951.
> Sounds like your setting Vgs to zero, right? That then results in 8mA?
> Over what voltage range?

Hi Harold,

Here's a link to some minimal 2N5951 data:
http://www.jameco.com/Jameco/Products/ProdDS/38527.pdf

Tie gate to either source or drain, JFETs don't really care, then just
treat it like a two-terminal device and put it in series with your LED. 8
mA is reached pretty quickly - the jfet has its on-resistance of about 100
ohms.

So your LED acts like it has a small resistor in series, until the point
the jfet starts to current limit(it's up to about 200 ohms with a volt
across it).

Current after that is solid at 8mA until I ran out of power supply at 15
volts.

I'm sure there are lots of jfets that would work, I only had two types on
hand to test.

If I had to guess, I'd bet the 2SK30A would work really well, but almost
all my analog stuff like that is in storage.

Cheers,

Bob

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