matching transistors - DIY

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elektrouwe
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Re: Anything to this idea?

Post by elektrouwe » Wed Dec 04, 2019 1:36 pm

jakobprogsch wrote:
consumer wrote: I read through this post, but never saw anyone respond to this idea: Is there any merit to multiplying the gain in order to exaggerate the offset?

Or would that just introduce more uncertainty?
I'd say no merit since at least the garden variety opamps that aren't specifically marketed as low offset probably have input offset specs in the mV range themselves.

I have to admit all this talk about the DMM digits in this thread has me confused anyway. Isn't the whole point of these "differential" circuits that you don't have to measure absolute voltage but only relative one? How many digits the DMM has is pretty irrelevant as long as it has a mV range setting.
true, matching is a relative measurement. That's why such a simple thing like YATMA can match to 50uV if you need it without precision DVM.
viewtopic.php?t=153845

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cygmu
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Re: Anything to this idea?

Post by cygmu » Thu Dec 05, 2019 2:07 am

elektrouwe wrote: true, matching is a relative measurement. That's why such a simple thing like YATMA can match to 50uV if you need it without precision DVM.
viewtopic.php?t=153845
I may have said this further up the thread, but: I love my YATMA! It is a very useful device and makes transistor matching actually enjoyable :) Thank you elektrouwe.

As a practical point, I have found the YATMA much easier and faster to use than my build of the Fritz circuit. Obviously it took a few more hours to put together but the time saved since and the reliable matches found are worth it, to me at least.

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jet
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Re: matching transistors - DIY

Post by jet » Fri Feb 07, 2020 1:17 pm

Is there a parts list/BOM for Ian Fritz's board available on OSHPark? I just order a batch of 3 and will probably have two to pass on.

I found this switch https://www.mouser.com/ProductDetail/Mo ... xlwcUaE%3D in an earlier post, maybe I can scrounge all the other parts at a hackerspace?
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KittenVillage
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Re: matching transistors - DIY

Post by KittenVillage » Sat Feb 08, 2020 5:10 pm

jet wrote:
Fri Feb 07, 2020 1:17 pm
Is there a parts list/BOM for Ian Fritz's board available on OSHPark? I just order a batch of 3 and will probably have two to pass on.

I found this switch https://www.mouser.com/ProductDetail/Mo ... xlwcUaE%3D in an earlier post, maybe I can scrounge all the other parts at a hackerspace?
I think I've got a couple of those switches I could pass on to you for one of your boards. I'll pm you.


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tenma
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Re: matching transistors - DIY

Post by tenma » Wed Feb 19, 2020 1:54 am

Hi, I bought an Ian Fritz transistor matching kit. I assembled the pcb but I'm wondering how I power it. It comes with a small ribbon cable, but what should I connect the ribbon cable to? Can I rig it to power of a 9V battery?

Thanks
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Re: matching transistors - DIY

Post by jorg » Wed Feb 19, 2020 12:16 pm

tenma wrote:
Wed Feb 19, 2020 1:54 am
Hi, I bought an Ian Fritz transistor matching kit. I assembled the pcb but I'm wondering how I power it. It comes with a small ribbon cable, but what should I connect the ribbon cable to?
That looks like a Eurorack power connector.

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jet
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Re: matching transistors - DIY

Post by jet » Sun Mar 08, 2020 11:17 am

I think this is the switch, ordered a few and will report back:

https://octopart.com/search?q=1MD1T6B11 ... SD&specs=0
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jurekprzezdziecki
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Re: matching transistors - DIY

Post by jurekprzezdziecki » Mon Sep 07, 2020 3:36 pm

Guys, how precise these 100k resitors should be? 0,1%? 0,01%? Thanks Jurek
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Synthiq
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Re: matching transistors - DIY

Post by Synthiq » Mon Sep 07, 2020 7:12 pm

If my calculations are correct, a 1% mismatch in current between the two transistors will result in a 0.26mV shift in the Vbe mismatch and with a 0.1% difference the error will be reduced to 0.026mV. What resistor tolerance you need depend on what accuracy you are aiming at.

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Re: matching transistors - DIY

Post by KSS » Mon Sep 07, 2020 10:40 pm

Or swap the mismatched resistor's positions and take note of the difference. As the Ian Fritz' document pointed out.

You're usually matching for equivalence, not absolute value. Don't feel the need to chase specs you don't really gain anything from.

Stick one tranny in, then a second. Keep the 1st in place and only change the second one. Equal meter readings are equal trannys from the 2nd position.
The R mismatch is accounted for in the result.

grab a cermet trimpot and put it between the two mismatche Rs.

A few different ways to address the situation.
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emmaker
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Re: matching transistors - DIY

Post by emmaker » Tue Sep 08, 2020 3:01 pm

jurekprzezdziecki wrote:
Mon Sep 07, 2020 3:36 pm
Guys, how precise these 100k resitors should be? 0,1%? 0,01%? Thanks Jurek
If you have a good ohm meter (probably don't need that good of one if it has fresh batteries, has enough digits and is consistent) you can use 1% resistors, just get a bunch. Basically you want the values to be the same, not an exact value, so if you have two resistors that measure 100.1K that will work. You probably want 0.1% difference and if you can get better there you are.

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Bartimaeus
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Re: matching transistors - DIY

Post by Bartimaeus » Tue Sep 08, 2020 8:58 pm

anyone have any spare fonik/ian fritz pcbs?

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Kevin Mitchell
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Re: matching transistors - DIY

Post by Kevin Mitchell » Wed Sep 09, 2020 1:16 pm

I'm going to have a round of PCBs for the MFOS Go/NoGo matching circuit. The parts are SMD. First version will be a simple NPN matching device.

PM me if interested so I'll know if I should increase my order. If anyone is apposed to the SMD version please let me know. I figured it would be a good circuit to practice my micro-soldering skills.

-KM

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Re: matching transistors - DIY

Post by KSS » Thu Sep 10, 2020 1:43 am

@Kevin Mitchell

Why did you choose arguably one of Ray's worst designs to go with? The YATMA and Fritz tranny matchers are so much better it makes no sense. I love Ray's work and have made use of it. But his tranny matcher? That's one to avoid, IMO.
Treat utility modules as stars instead of backup singers.
Treat power supplies like Rockstars instead of roadies!
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Kevin Mitchell
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Re: matching transistors - DIY

Post by Kevin Mitchell » Thu Sep 10, 2020 7:04 am

KSS wrote:
Thu Sep 10, 2020 1:43 am
@Kevin Mitchell

Why did you choose arguably one of Ray's worst designs to go with? The YATMA and Fritz tranny matchers are so much better it makes no sense. I love Ray's work and have made use of it. But his tranny matcher? That's one to avoid, IMO.
Please do explain.

Once the circuit and test transistors are stabilized I see no reason why it isn't a sufficient circuit for matching transistors. Especially with appropriate offset trimming and the math checks out.

Trust issues with the window comparator? I find it fine as is but we can narrow the window for tighter matches.

Don't like the 10v supply circuit? Me neither so I won't be using that design.

-KM

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Re: matching transistors - DIY

Post by KSS » Thu Sep 10, 2020 10:07 am

While you're doing all that, someone with a Fritz method will have already tested and matched all the transistors they need. The MFOS design is over-complicated and relies on a whole lot of parts. For what?

What is it that it provides that the -as I already said much simpler and much better Fritz and YATMA- do not?
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Kevin Mitchell
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Re: matching transistors - DIY

Post by Kevin Mitchell » Thu Sep 10, 2020 12:45 pm

KSS wrote:
Thu Sep 10, 2020 10:07 am
While you're doing all that, someone with a Fritz method will have already tested and matched all the transistors they need. The MFOS design is over-complicated and relies on a whole lot of parts. For what?

What is it that it provides that the -as I already said much simpler and much better Fritz and YATMA- do not?
A red and green LED to show matches... duh...

There's a gap here between practicality and amusement. I've done everything from matching transistors using the meter diode setting to building up the simple measuring circuits - and probably still have Ian's circuit collecting dust somewhere.

Leave it to the rest of us who enjoy tinkering and bright shiny things. All in all - I find it to be an educational, fun circuit. A more enjoyable build than the alternatives. To each their own. I just know mine is more cool than yours. And it's certainly not inferior to the others. Just more complicated.

If it's inferior to you because it uses more parts - then you surely have no appreciation for what it is. If all you want is to match transistors, by all means take the easy route. But I've got the cool red light green light matcher that I had built and learnt from. If that isn't enough for ya, stick to your two resistor circuit.

-KM
Last edited by Kevin Mitchell on Thu Sep 10, 2020 1:12 pm, edited 3 times in total.

KSS
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Re: matching transistors - DIY

Post by KSS » Thu Sep 10, 2020 12:53 pm

It *is* inferior. But knock yourself out! Fun *is* a good enough reason to do so. :party:
Treat utility modules as stars instead of backup singers.
Treat power supplies like Rockstars instead of roadies!
Chase magic sound, not magic parts.

jurekprzezdziecki
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Re: matching transistors - DIY

Post by jurekprzezdziecki » Mon Oct 12, 2020 11:38 am

Bartimaeus wrote:
Tue Sep 08, 2020 8:58 pm
anyone have any spare fonik/ian fritz pcbs?
message me if you still interested
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