[sdiy] Transistor matching Was: Another satisfied Takuya Katayama Tempco customer.

Mon Jul 21 19:14:17 CEST 2008

If you want "Super-matching" you should not even consider two
discrete transistors, as you need them to be at precisely the
same temperature.

Buy a monolythic dual transistor if you ned the matching to be, and
remain that good.

Why do you think the even ~make~ monolythic duals ???

The only way you can justify hand matching is to save a few pennies.
For any production use (or to sell them to others) it would be useless.

Think... they built an awful chip like the MM5837 noise source because
it was too costly to choose ~one~ transistor for a quality like
"it sounds good"   ;^P

H^) harry

On Sat, 19 Jul 2008 17:19:42 +0200, Csaba Zvekan wrote
> Damian,
> 
> Thanks Damien, ..lol...Yeah I didn't think of that. Labeling &  
> packaging of the super matched  transistors . :)
> You will laugh cause I really have some barcode readers laying 
> around  for a couple of years now. I remember scavenging an old CD 
> label /  sorter factory. That's where  I got them from  .Up until 
> now I had no  idea what to do with them. :) No, but seriously that 
> transistor project  is awesome and credit goes  for that wonderful 
> man who designed the thing. Also I am nothing compared to these 
> people on the SDIY list. They are  the real miracle makers . I am 
> just a good copy cat :) and feel like  information and knowledge 
> should be free and shared. Cause at one  point it was freely shared 
> to me.
> 
> Csaba
> 
> On Jul 19, 2008, at 3:11 PM, cheater cheater wrote:
> 
> > Csaba,
> > I assume it would also have to label each part that's being matched to
> > keep an inventory. Some sort of barcode system, presumably. So, you'd
> > need a barcode reader in there as well.
> > All your projects seem pretty cool :) I'm quite impressed. And if you
> > do make an automated matching facility, make sure to let us know :D
> >
> > Cheers
> > Damian
> >
> > On 7/18/08, Csaba Zvekan <czvekan at gmail.com> wrote:
> >> Ohh that's no problem I also thought of that as well . :) ...lol...
> >>
> >> see my DIY CNC/ SMD pick and place project :
> >>
> >> http://www.youtube.com/watch?v=hOVnKK6m5a4
> >>
> >> ...lol..
> >>
> >>
> >> Just kidding it just mills and drills ... could be modified   
> >> though :)
> >>
> >> Csaba
> >>
> >>
> >>
> >> On Jul 18, 2008, at 10:00 PM, cheater cheater wrote:
> >>
> >>
> >>> The only thing we need now is to come up with a robotic arm to load
> >>> transistors from SMD mounting tape, then we can run&forget for two
> >>> weeks and have a very nicely matched bulk of transistors. :)
> >>> I assume this is what companies normally use to match them?
> >>>
> >>> Cheers
> >>> Damian
> >>>
> >>> On 7/18/08, Csaba Zvekan <czvekan at gmail.com> wrote:
> >>>
> >>>> Ian ,
> >>>>
> >>>> I am by now means an electronic guru . And can not answer your  
> >>>> question.
> >>>> All I know is that I have matched some transistors (BC547) for a  
> >>>> VCO
> >> project
> >>>> (Yves VCO Yusynths
> >>>> http://yusynth.net/Modular/EN/VCO/index.html
> >>>> and compared with the LM394 SuperMatched Pair) . And find no  
> >>>> noticeable
> >>>> difference in temperature drift or anything.
> >>>> The only difference is the price  compare for yourself LM394 is  
> >>>> 22.35$
> >> and
> >>>> two BC547 is 0.20$ . Ok you would still need to purchase a bunch to
> >> compared
> >>>> them. But you get the idea.
> >>>> All though I must say that the precision OP-AMP OP490  is rather
> >> expensive
> >>>> ( 15.70$ @ farnell.com )  :( but hey , we want precision, right ?  
> >>>> And
> >> it's
> >>>> not like we need to buy hundred of them. The rest of the project is
> >> rather
> >>>> cheap .
> >>>> Make sure you handle measuring in the morning and touch the  
> >>>> transistors
> >>>> with tweezers. Also give it some minutes to settle . You 'll get  
> >>>> the
> >> hang of
> >>>> it.
> >>>> The original design I got from here:
> >>>>
> >>>>
> >> http://electronicdesign.com/Articles/Index.cfm?AD=1&AD=1&ArticleID=6251
> >>>>
> >>>> Csaba
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> On Jul 18, 2008, at 4:24 PM, Ian Fritz wrote:
> >>>>
> >>>>
> >>>>
> >>>>> At 05:29 AM 7/18/2008, Csaba Zvekan wrote:
> >>>>>
> >>>>>
> >>>>>> We SDIY people always need matched transistor pairs :
> >>>>>>
> >>>>>> that's why I recommend this:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>
> >>>>
> >> http://www.csaba.ch/index.php?option=com_content&task=view&id=14&Itemid=30
> >>>>
> >>>>>
> >>>>>>
> >>>>>>
> >>>>>
> >>>>> Is there some advantage of this over a simple bridge circuit?  How
> >>>>>
> >>>> precisely can you measure the matching?
> >>>>
> >>>>>
> >>>>> Ian
> >>>>>
> >>>>>
> >>>>
> >>>> _______________________________________________
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> >>>> Synth-diy at dropmix.xs4all.nl
> >>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> >>>>
> >>>>
> >>>
> >>
> >> _______________________________________________
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> >>
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Harry Bissell & Nora Abdullah 4eva