[sdiy] Matched Trannies

Wed Jul 3 17:06:41 CEST 2002

You need matched trannies... some SMT packages
are just two transistor die in the same plastic
package.

The dual transistors in the same package would have
good thermal matching and 'might' have good electrical
characteristics as well, you would have to test them
to find out.

I tried some quad (non-monolythic) trannies that seemed
to be pretty good (probably sliced from the same wafer)

I don't KNOW if the part numbers you mentioned are monolythic
or not... you have to ask the manufacturer.

H^) harry

--------Original Message--------  

From: Yves.Usson at ujf-grenoble.fr
To: synth-diy at dropmix.xs4all.nl
Sent: Jul 3 2002 16:10
Subject: [sdiy] Matched Trannies

>Hi
>When one needs a matched pair of transistors (PNPs or NPNs) for 
>designing an expo converter or
>for a moog transistor ladder the existing solutions are SSM2220, 
>SSM2210, MAT03,
>MAT04,2SC1583,THATxxxx... These are quite expensive. A cheap solution for NPN
>matched pair is to use CA3046 or CA3086. Recently, I found another 
>possible source of
>matched transistors these are SMD components labelled BC857S 
>(siemens, supposed to
>be equivalent to two BC557 PNP) and BC847S (siemens, supposed to be 
>equivalent to two BC547 NPN). These are real cheap : 0.18 euros 
>(nearly 0.17$).
>My question is the following :
>Is there a good reason why I should not use these for designing expo 
>converters or moog ladders ?
>As someone in the list gave them a try ?
>Thanks for your input
>-- 
>----------------------------------------------------------------------------------------------------------------------------
>Dr Yves USSON						ph. +33 476 549 410
>Equipe RFMQ, TIMC UMR5525 CNRS				fax. +33 476 549 549
>Institut Albert Bonniot, Domaine de la Merci
>38706 La Tronche cedex, FRANCE
>  http://www-timc.imag.fr/rfmq/PAGES/Y-USSON/