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

[cheater cheater]

Harry,
but don't those thing become difficult to source after about two weeks? :(
Cheers
Damian

On Mon, Jul 21, 2008 at 6:14 PM,  <harrybissell at wowway.com> wrote:
> 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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>> >>>>
>> >>>>
>> >>>
>> >>
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>
> Harry Bissell & Nora Abdullah 4eva
>
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