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

[Jay Schwichtenberg]

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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> Synth-diy at dropmix.xs4all.nl
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