Anyone have any thoughts on using a Hypex SMPS400a400, 1 per channel? I will also be using the micro ripple eater, 1 per channel. Or suggestions on another high quality SMPS? I looked at CONNEX but shipping to Canada is way to much. Thanks
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.
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.
Attachments
Getting through the IPS 🙂. Leaving the transistors till last though.
I have uploaded a new BOM. No component changes.
Fireanimal suggested connectors that use 10mm standoffs for SIP1.
Fireanimal suggested connectors that use 10mm standoffs for SIP1.
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.
Attachments
Hi, I remember that the only couples of resistors that need to be matched are R3,4 and R7,8
Am I losing something?
Thanks, Gaetano.
Am I losing something?
Thanks, Gaetano.
No your right... I'm just ocd. I like the values to be exact as possible. Some buy .1% and it's good I get 1% resistor and measure to find the best.Hi, I remember that the only couples of resistors that need to be matched are R3,4 and R7,8
Am I losing something?
Thanks, Gaetano.
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 🙄 it catches the light and looks awful !
Hope everyone is going well with their build(s)
- Dan
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 🙄 it catches the light and looks awful !
Hope everyone is going well with their build(s)
- Dan
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.
I would like one, thank youI 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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