The long lost 2SK 30(O)

[*Star Project]

ok so by trimming R35 one can get the same wave as the O part
gives with the Y part. Well it could be worth doing this I guess
rather than hunting down that damn O part. what value should this
trimmer be anyway? I think I'll start by comparing it to my
real 303 at first and then turning that trimmer a little more
to see if I can find something that really turns me on more
than the original, if there is such a setting.

Thanks all especially you Trev. Never thanked you for that
pot and DIN tip. thx

/ Andreas

-----Ursprungligt meddelande-----
Från: owner-synth-diy at node12b53.a2000.nl
[mailto:owner-synth-diy at node12b53.a2000.nl]För Fraser, Colin J
Skickat: den 16 november 2000 15:56
Till: 'Trevor Page'; DIY skicka Lista
Ämne: RE: The long lost 2SK 30(O)


> -----Original Message-----
> From: Trevor Page [mailto:trevor at resonance.fsnet.co.uk]
> Sent: 16 November 2000 11:28
> To: Fraser, Colin J; *Star Project; DIY skicka Lista
> Subject: Re: The long lost 2SK 30(O)
>
> I guess it is down to luck. I must have been fortunate to get
> a batch of -Y variants which happened to make a good
> substitute for the -O! I used -Y's in my TB3030's and got
> good results, i.e. producing squarewaves of the correct
> pulsewidth. Placing a trimmer in the differentiator circuit
> is a good idea. I stuck a trimmer in place of R35 and then
> managed to get several JFETs to work. Trim for a nice 50%
> duty cycle, but remember this varies with frequency anyway.

And as Tony said, the component tolerances mean different 303s will differ
slightly too.
My clone is adjusted to sound the same as my real 303.
Whether it sounds the same as any other is another question.

It might be worthwhile having a sample of a reference 303 squarewave at a
given pitch somewhere...

Colin f