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

Sat Jul 19 18:39:14 CEST 2008

Hmm, so there's no way to modify this to make it automatic? :)

On Sat, Jul 19, 2008 at 5:17 PM, Csaba Zvekan <czvekan at gmail.com> wrote:
>
> On Jul 19, 2008, at 5:44 PM, cheater cheater wrote:
>
>> Hmm, I assume just testing each transistor on its own and recording
>> parameters wouldn't be good enough.
>
> No
>>
>> You really need a circuit of two
>> transistors, don't you?
>
> Yes you pick two random transistors and compare the two with your dual
> channel oscilloscope. Superimpose the curve and give them a note let's say
> from 1 to 10 . Then you would bag them and take the best matched ones for
> your projects.
> I even have a few extra pre matched bags with labels saying 8.5 or 9 or
> something on them . That way next time I don't even have to match them. It's
> already done. But it's really fun to do it and easy as well.
>
>>
>>
>> How would you go about testing each pair? You'd have to have some sort
>> of serving facility to store and serve the parts somehow.
>>
>> Best regards,
>> Damian
>>
>>
>> On Sat, Jul 19, 2008 at 4:19 PM, Csaba Zvekan <czvekan at gmail.com> 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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