DIY Class A/B Amp The "Wolverine" build thread

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greglo3a

Member
Joined 2020
anatech said:
Hi Garethllywelyn,
Some years ago I designed a transistor matching jig and gave the design to the community here. It is very effective and there have been a few boards designed for it. I think there was a thread with an Adcom GFA-565 that covered it, and possibly other threads.

When matching transistors, it is critical they are at identical temperatures. They must be compared at the same time precisely. Using a beta test function cannot achieve this and you would be surprised at how far apart those matched parts can be. Often better than just fishing out a pair, but not really matched.

I just made differential pair with a current source for tail current. You measure between the collectors using a meter which becomes a null detector. The collector loads are 0.1% resistors and matches better than 1% can be made easily. This process has a thermal component, so time must be allowed to have the devices settle into thermal equilibrium. I pre-sort my parts using a beta test and group similar gains, then run through that pool. The two parts are placed in direct contact with each other and a foam "hat" placed over them. The entire test setup is then covered with a box (bowl or whatever) to block air currents. It uses a bipolar power supply, but a pair of 9V batteries would work also. I typically run abound 11 VDC trying for a 10 V collector - emitter drop across the parts.

The DUT jacks are critical, you have to use good quality ones from a proper supplier. I have tried various Asian sources and they are all poor quality so far. There is a circuit for PNP and another for NPN. The jacks are laid out so they can accommodate all pin outs, four contacts each.

I'll try to find some information on it.
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greglo3a

Member
Joined 2020
I remember, I had a bunch of pcb made of an older version, so this is not the current version. With Anatech's permission, I can make the unpopulated pcb available to anyone that wants one. I have 27 pcb available. But remember, this is not the the most up to date version and I won't offer the pcb if Anatech says no.
 

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fireanimal

fireanimal

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Joined 2008
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Made some progress, SMD caps and R00,R0,R22 Installed, links, vias and jumpers done on 6 boards! I am matching all resistors as best I can. I ordered 100 pcs of MBB0207 series and was able to get R00 matched to <.001% and R0,22 to <.01%. So looking good for those resistors at 12 cents Canadian a piece.
 

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danieljw

danieljw

Member
Joined 2005
Some progress today.....

I am in the middle of making the next build video but here is where my build is at after making the input stage PCBs, I have started on the main board.
Please excuse the flux which is not cleaned off yet :rolleyes: it catches the light and looks awful !

1652623083249.jpeg


Hope everyone is going well with their build(s)

- Dan
 
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greglo3a

Member
Joined 2020
I just got the ok from Anatech, to offer his transistor matching design pcb, it is unpopulated and I only have 18 pcb, so first come first serve. The documentation is buried within this website, I can assist in finding it. I'm asking for the cost of shipping and materials from USA, which will vary if your overseas. But if your in the US, I don't see my expenses being more than $8 using USPS first class. To be fair, I'm limiting one pcb per member. Remember I only have 18 boards.
 
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1883

Member
Joined 2017
greglo3a said:
I just got the ok from Anatech, to offer his transistor matching design pcb, it is unpopulated and I only have 18 pcb, so first come first serve. The documentation is buried within this website, I can assist in finding it. I'm asking for the cost of shipping and materials from USA, which will vary if your overseas. But if your in the US, I don't see my expenses being more than $8 using USPS first class. To be fair, I'm limiting one pcb per member. Remember I only have 18 boards.
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I would like one, thank you
 
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