[sdiy] Vco I did today...

[Ian Fritz]

If you look at the comparison chart given by Farichild, you will see that 
25 different parts come from that one process (No. 51).  Most are not all 
that suitable for the sawtooth VCO application.  I think the best devices 
are the 2N4391, 2N4859, 2N4091 (all from process 51) and the2N5432 (process 
58). To me, the J111 has too much leakage and too little pass current.  A 
couple of weeks ago I looked around and found that three manufacturers are 
still producing the 2N4391, which is my choice for the best unit.

   Ian


At 12:00 PM 1/16/2003, Tim Ressel wrote:
>Jim,
>
>I don't think the J111 and 2N4391 are the same. J111
>shows 1nA Idoff, 2N4391 is 0.1nA.
>
>You're right, Rdson and Idoff tend to be exclusive.
>But it makes sense; the combination can be thought of
>as the dynamic range of the FET. The question I have
>is: which is more important, Rdson or Idoff?
>
>--tr
>
>--- patchell <patchell at silcom.com> wrote:
> >     I have had no problems with them.  The J111 is
> > equiv (well, actually
> > the same die as) the 2n4391 which has also been used
> > a lot.