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Tranny matching questions
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MapacheRaper



Joined: Feb 15, 2018
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PostPosted: Wed Aug 08, 2018 7:07 pm    Post subject: Tranny matching questions Reply with quote  Mark this post and the followings unread

Hi,

Im trying to match trannies following the attached Ian Fritzs circuit, but I get nonsense readings. Like 1.4V and going up throught until 1.6V. The readings keep rising over the minuts and never stops.

I understand it should be reading around 0.6/0.7V correct?

Now Im planning to breadboard this:

Posted Image, might have been reduced in size. Click Image to view fullscreen.


But I dont have the zener. Could it work without it?. What´s the zener function here?. I can use a regulated power supply to put exactly some random voltage to the circuit, so if it needs 5.1V I can supply exactly this.

Where should I put the probes in the opamps circuit?

Im a bit lost. Thanks!


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wackelpeter



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PostPosted: Thu Aug 09, 2018 1:27 am    Post subject: Reply with quote  Mark this post and the followings unread

that the measurements move slightly is partially due to temperature changes...

You will like to rest the trannies a while in their circuit before you measure them... whenever you touch them the voltage will change ad then it takes some time to settle to the ambient temperature...

I have build the transistor matcher from Elektrouwe, the linke was posted here and found that many of my matched transitors via the method you like to use showed some discrepancies... either i was to stupid to do it properly, my DVM not being the best suited for it, or i wasn't waiting long enough for them to settle...

with the circuit by elektrouwe you also have to wait until they settle, but i find it quiet easier to match with them and you can also get pretty close detailed readings your typical average DVM wouldn't be capable to show...


Only disadvantage, you'll need an oscilloscope...

MAybe Ian Fritz can tell you more, guess he's sometimes still visiting here and can expalin again or say what i/we did wrong, then hopefully getting it then.

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Blue Hell
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PostPosted: Thu Aug 09, 2018 1:36 am    Post subject: Reply with quote  Mark this post and the followings unread

You really need the zener diode as it makes the reference voltage needed for the measurement. And also do use a 5v1 one, as around that zener voltage the zener's temperature dependency is as small as possible.
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JovianPyx



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PostPosted: Thu Aug 09, 2018 6:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Knowing who Ian Fritz is, I'd say that there are no components in this circuit that can be casually eliminated including the zener diode.
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MapacheRaper



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PostPosted: Thu Aug 09, 2018 6:09 am    Post subject: Reply with quote  Mark this post and the followings unread

@wackelpeter

I ordered an DSO150 osci, but it was DOA. I´ll be getting one in other moment, thought. I´ll check the matcher. Thanks!


@bluehell. I´ll search for the zener. Thanks for the explanation!
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g.gabba



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PostPosted: Fri Aug 10, 2018 9:25 am    Post subject: Reply with quote  Mark this post and the followings unread

as the zener is working to produce a stable and supply-voltage-independent voltage-reference @5V, and it is only connectet to the positive inputs of the opamps - u could just use a trimmer to produce that 5V


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MapacheRaper



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PostPosted: Fri Aug 10, 2018 5:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

That´s a sweet idea. I have a bunch of zeners coming, but maybe Im breadboarding this so I can finish some building

I will try with a 50k pot

Thanks g.gabba!
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wackelpeter



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PostPosted: Fri Aug 10, 2018 10:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

I wonder how much influence a mismatch in the Zeners would have on the measurements… At least i'm unaware if there is some difference of a few mV in the Zeners and if it's too marginal to care of.
Well my guess is that it is not much or has effectively no effect on the measurements, but i'm not Pretty sure.

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AlanP



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PostPosted: Sat Aug 11, 2018 12:04 am    Post subject: Reply with quote  Mark this post and the followings unread

http://www.dragonflyalley.com/synth/images/TransistorMatching/ianFritz-transmat0011_144.pdf

For clarity -- that schematic shown on this thread is misleading as hell.

When matching transistors, do it while watching a mildly boring movie. Leave five minutes after you've placed a transistor to measure it.

10 stick transistor in socket
20 wait 5 minutes
30 measure transistor
40 put transistor on some tape with a note of it's reading
50 get a new transistor
60 goto 10

Also, leave your reference transistor in there permanently. All your measurements will be with that one as a reference.
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g.gabba



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PostPosted: Sat Aug 11, 2018 12:45 am    Post subject: Reply with quote  Mark this post and the followings unread

RUN MATCH.BAS
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wackelpeter



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PostPosted: Sat Aug 11, 2018 2:20 am    Post subject: Reply with quote  Mark this post and the followings unread

AlanP wrote:
http://www.dragonflyalley.com/synth/images/TransistorMatching/ianFritz-transmat0011_144.pdf

For clarity -- that schematic shown on this thread is misleading as hell.

When matching transistors, do it while watching a mildly boring movie. Leave five minutes after you've placed a transistor to measure it.

10 stick transistor in socket
20 wait 5 minutes
30 measure transistor
40 put transistor on some tape with a note of it's reading
50 get a new transistor
60 goto 10

Also, leave your reference transistor in there permanently. All your measurements will be with that one as a reference.


don't you have to switch the trannies in their sockets to get the difference in your measurements??? means trannie which was sticked into socket a must be sticked then into socket b and the other trannie vice versa? due to the nature of that we don't have an ideal=equal reference voltage at both trannies? So you have to substract delta UBE 1 from delta UBE2 to get the mismatch of the trannies?

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AlanP



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PostPosted: Sat Aug 11, 2018 3:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Naw, leave Q2 permanently stuck. Just endlessly replace Q1 and measure.
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wackelpeter



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PostPosted: Sat Aug 11, 2018 5:45 am    Post subject: Reply with quote  Mark this post and the followings unread

yep okay, was a bit off my mind... it's of Course way easier and much more useful to just swap the probes of the DVM...
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MapacheRaper



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PostPosted: Mon Aug 13, 2018 1:48 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok, while breadboarding I have realised that this tester is for single +- supply.

I have modified it for + ground - supply, so the zener is not needed.

I have also added where the probes goes for newbies clarification. Now it reads perfectly.


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Blue Hell
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PostPosted: Mon Aug 13, 2018 2:12 am    Post subject: Reply with quote  Mark this post and the followings unread

That is a good solution too - great you got it working :-)
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MapacheRaper



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PostPosted: Mon Aug 13, 2018 3:53 am    Post subject: Reply with quote  Mark this post and the followings unread

Very Happy









cheeeezeeey
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g.gabba



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PostPosted: Mon Aug 13, 2018 7:52 am    Post subject: Reply with quote  Mark this post and the followings unread

or do, what sir yves has once suggested
http://electro-music.com/forum/post-372850.html
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MapacheRaper



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PostPosted: Mon Aug 13, 2018 1:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

thanks
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