[sdiy] hand matching transistors

[Ray Wilson]

Here is a thread from a while back. Lots of good stuff in here about 
matching. Some links to test rigs etc..




I offer them for sale as well...

http://www.oldcrows.net/~patchell/parts/parts.html

At 07:57 PM 4/26/2005 -0700, Bob Weigel wrote:
>Great page Jim.  I've never seen that somehow. I added it to my general
>links on the front page..in fact it inspired me to actually put in such a
>section :-).  One note...DigiKey no longer has CA3280 or E coming up on
>their links.  Not sure why.  Those are still in production as per
>Intersil's page.  I just got some stock from Arrow in case people need
>them while ordering other things or I need them along the repair 
>trail. -Bob
>
>James Patchell wrote:
>
>>http://www.oldcrows.net/%7Epatchell/matcher/matcher.html
>>
>>At 04:30 PM 4/26/2005 -0700, Harry Bissell Jr wrote:
>>
>>>Really, what you want to do is match for the same
>>>base-emitter voltage drop at some particular test
>>>current that is in the range you will use. Usually
>>>100uA is a good place to start.
>>>
>>>Pass 100uA through the base-emitter junction and
>>>measure the voltage. Pair those that are within
>>>1mV or so.
>>>
>>>There are schematics online for the test jigs that
>>>Bob Moog etc used to do this. Fess' up if you've
>>>got them on your site.
>>>
>>>Higher beta is better for other reasons, but usually
>>>no for matching.
>>>
>>>DO NOT touch the transistors you will test, the warmth
>>>of you hands will change the reading VERY much. Use
>>>tweezers or something like that.  I have used the
>>>Pomona "mini hooks" to pick up the part by its leads,
>>>Don't test in sunlight, or drafty place, or near heat
>>>vent.
>>>
>>>Once you match transistors, use them in pairs and its
>>>best to tie them together with epoxy, or a copper clip
>>>(hard to find these days) or thermal compound between
>>>them... or I sometimes use thermal compound and a
>>>little piece of heat shrink tubing over them.
>>>
>>>If it is for an expo converter, the tempco should be
>>>thermally coupled as well.
>>>
>>>I use the 2SC1583 (NPN pair) and 2SA798 (PNP pair) as
>>>alternatives to matching (they ARE matched) but have
>>>the emitters tied to one pin (good for expos, bad for
>>>Moog ladder...)  The 2SC3381 and 2SA1349 are good
>>>pairs that are separatr.  The CA3046 is a five
>>>transistor package in a 14 pin dip, matching and
>>>thermal coupling are quite good.  Cost of the 3046 can
>>>be as low as $.25 in 100pcs. lots  (cheap  !)
>>>
>>>Good luck
>>>
>>>H^) harry
>>>
>>>
>>>--- Fiercefish <fiercefish at btinternet.com> wrote:
>>> > Thanks to all who replied, I have tested a bunch of
>>> > the transistors and the hFE varied from about 130 to
>>> > 200, I found about 8 that matched at 166, do you
>>> > reckon this would be ok to use in the soundlab
>>> > VCO's? From what I can gather a matching hFE is
>>> > better than just randomly sticking any pair in but
>>> > not as precise as the traditional method, no?
>>> >
>>> > Also re the tempco's would these be suitable?
>>> >
>>> >
>>>http://www.maplin.co.uk/Module.aspx?ModuleNo=2218&TabID=1&source=15&WorldID=&doy=26m4&Cache=#CacheID
>>>
>>> >
>>> > The design calls for 2k PTC but would I be able to
>>> > use the 4.7k above if I changed the circuit a bit?
>>> > Any thoughts welcome!
>>> >
>>> > BTW I promise to post some pics up when I finally
>>> > finish the Soundlab, it will look pretty cool in a
>>> > nice old hardwood cigar box with an aluminium panel
>>> > and cool wide skirt numbered knobs.
>>> >
>>> > FF> No virus found in this outgoing message.
>>> > Checked by AVG Anti-Virus.
>>> > Version: 7.0.308 / Virus Database: 266.10.2 -
>>> > Release Date: 21/04/2005
>>> >
>>
>>
>>         -Jim
>>***************************************************************
>>http://www.oldcrows.net/~patchell
>>
>>***************************************************************
>>
>>
>>
>
>         -Jim
>***************************************************************
>http://www.oldcrows.net/~patchell
>
>***************************************************************






----- Original Message ----- 
From: "Jeff Farr" <moogah at gmail.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, July 12, 2005 11:33 PM
Subject: [sdiy] hand matching transistors


> So, I just got a pile of TIS97's in the mail in hopes of making a
> MiniMoog filter.  Question is, how best to hand match them?  Currently
> I plan on testing the beta of each and taping like pairs together by
> their leads (using masking tape).
>