[sdiy] Moog VCHPF pole's NPN/PNP matching

[Jean-Pierre Desrochers]

Hi Jay,

> 2N3904s and 2N3906s don't have complementary gain curves
Well everywhere on the web they state 2N3906 as complementary for 3904 
(???)

> If you want to match the PNPs and NPNs then something like
> BC549/BC550 BC559/BC560 are better choices.
I will follow your advice on that...

Thanks.
JP

Le 2014-04-22 11:42, Jay Schwichtenberg a écrit :
> JP,
> 
> I don't think you have to match the PNPs and NPNs gain wise. Think you 
> just
> have to match NPNs to NPNs and PNPs to PNPs. 2N3904s and 2N3906s don't 
> have
> complementary gain curves so that will be hard to do anyways. If you 
> want to
> match the PNPs and NPNs then something like BC549/BC550 BC559/BC560 are
> better choices.
> 
> Also did you use the corrected Moog schematic for the transistor 
> tester?
> 
> http://www.dragonflyalley.com/constructionTransistorMatching.htm
> 
> Might check this out also:
> 
> http://home.comcast.net/~ijfritz/MiscProj/transmat001.pdf
> 
> Jay S.
> 
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Jarno 
> Verhoeven
> Sent: Tuesday, April 22, 2014 7:44 AM
> To: synth-diy; Jean-Pierre Desrochers
> Subject: Re: [sdiy] Moog VCHPF pole's NPN/PNP matching
> 
> BC847PN might be an option, not matched though, and SMT (AND pretty 
> d*mn
> small).
> Apparently matching NPN/PNP is always a problem. Even THAT corp do not
> specify
> matching across PNP/NPN pairs in their THAT340.
> 
> Jarno.
> 
> 
>> Op 22 april 2014 om 15:15 schreef Jean-Pierre Desrochers
> <jpdesroc at oricom.ca>:
>> 
>> 
>> Did anybody build a Moog 904B VCHPF circuit?
>> The schematic states that all the NPN/PNP pairs
>> used in the 4 poles chain (Q13,14 Q17,18 Q21,22 Q25,26)
>> needed to be matched pairs.
>> See the circuit here:
>> http://www.freeinfosociety.com/electronics/schemview.php?id=944
>> 
>> I read lots of threads on the list about this issue
>> with no findings ..
>> Well I matched a lot of NPN pairs (2N3904)
>> and PNP pairs (2N3906) last weekend using Bob Moog's
>> little matching setup with very good results
>> (better than 2mv in matching values !) but I'm having
>> a hard time to match NPN/PNP pairs in my lot..
>> The 2N3904 batch are around .600v @ 100uA
>> but the 2N3906 batch are around .650v @ 100uA.
>> Anybody knows good complimentary pairs available
>> or a way to compensate for the vbe differences ?
>> I'm considering specialised NPN/PNP IC matched pair.
>> 
>> JP
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