TB303 vco pt2

[Arthur Harrison]

Another good N-ch. JFET is the 2N5484, with a Vg-s(off) of 3v max.
And, it's very inexpensive and generally available.

Art

-----Original Message-----
From: jhaible <jhaible at metronet.de>
To: Tony Allgood <oakley at techrepairs.freeserve.co.uk>; synth diy
<synth-diy at mailhost.bpa.nl>
Date: Wednesday, November 18, 1998 6:01 PM
Subject: Re: TB303 vco pt2


>> some time. However, once I put the FET in, differences were evident. I
>> used a BF244 and then a 2N3819. Both n-type JFETs. Firstly, the flat
>> part of the sawtooth output was now obvious. The time of the flat was
>> frequency dependent, but then again it would because the FET follower
>> could follow the input. I always thought there will always be a
>> noticeable Vgs between input and output in a source follower. Surely if
>> the sawtooth is at 12V, the supply, the FET output will not be able to
>> follow.  What type of FET are Roland using? Is this 2SK30 not a JFET? Or
>> am I completely missing the point here?
>
>Try different types of BF244. A BF244A can have as low as 1.5V threshold,
>while a BF244C can have 6V and more. (from memory; exact range see data
>sheet).
>
>JH.