Replacement JFET for ASM-1 VCO

Harry Bissell harrybissell at
Wed Nov 3 03:35:31 CET 1999

I've been trying various Spice models of FETs... and some work much better than
Oddly the 4391 is one of the best... I don't know what parameter or parameters
make the magic happen yet...
And the bipolar works better than all of them... Why do people like FETs so
P.S... the VN1206 mosfet from Siliconix works well too (in simulation) if you use
the 12V drive level and 6V reset level like some Moogs do...

:^) Harry

Dr Steve Grainger wrote:

> Dear All,
>         Found an interesting page on Siliconix's site :-
>         This has the data for their 'switching' JFETs and the J109 looks
>         a good replacement for the 4391 type (and its available from Maplin
>         Electronics in the UK) In fact it seems to have a LOWER ON resistance.
>         I'll try and buy some tomorrow and report results later this week.
>         Regards
>         Steve Grainger
> Dr Steve Grainger
> Midlands ED and MiB Support Centre Manager
> School of Engineering and Advanced Technology
> Staffordshire University
> Beaconside
> Stafford
> ST18 0AD
> Tel.   +44 (0) 1785 353636
> Fax.  +44 (0) 1785 353551

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