matching transistors - DIY

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Fernando
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Post by Fernando » Sun Jul 29, 2018 12:13 pm

thank you very much.

So with 4k7 and +-15V we'll have the same current than with 3k9 and +-12V?
.

Fer

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cygmu
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Post by cygmu » Sun Jul 29, 2018 1:59 pm

Fernando wrote:thank you very much.

So with 4k7 and +-15V we'll have the same current than with 3k9 and +-12V?
Pretty much:

(12-0.6)/3.9 = 2.92
(15-0.6)/4.7= 3.06

140 microamperes difference :( It’s not critical anyway: use any resistor around that value that you happen to have.

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Fernando
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Post by Fernando » Sun Jul 29, 2018 2:20 pm

great, thanks
.

Fer

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phisynth
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Post by phisynth » Fri Sep 21, 2018 4:11 pm

I'm planning to build Ian Fritz circuit on stripboard including DPDT switches, could somebody have a look at this to check if I'm good ?

Thanks !

Image

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meatcliff
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Post by meatcliff » Mon Oct 29, 2018 2:10 pm

Anyone in the US have a spare PCB based on Fritz's method they'd like to trade?

I've got plenty of junk and PCBs to send in exchange and would rather avoid ordering off oshpark.

Thanks!

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Fernando
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Post by Fernando » Tue Oct 30, 2018 8:00 pm

I have a pcb to let go
but I'm in Europe
.

Fer

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devinw1
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Post by devinw1 » Tue Oct 30, 2018 10:54 pm

meatcliff wrote:Anyone in the US have a spare PCB based on Fritz's method they'd like to trade?

I've got plenty of junk and PCBs to send in exchange and would rather avoid ordering off oshpark.

Thanks!
I’ve got 10 sitting here and haven’t even built one yet haha! You can definitely have one

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meatcliff
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Post by meatcliff » Thu Nov 01, 2018 7:53 pm

Thanks! Will PM shortly.

aabbcc
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Post by aabbcc » Wed Nov 07, 2018 9:15 am

Quick question, is my DVM up to par for selecting transistors with no more than 2mv difference using the ian fritz circuit? Am I reading the spec right that its accurate for +/- 2mv or what does the +2d mean?

Image

It's a brymen 867s, 5-4.5d resolution, 500'000 count.

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Post by Synthiq » Wed Nov 07, 2018 10:55 am

aabbcc wrote:Quick question, is my DVM up to par for selecting transistors with no more than 2mv difference using the ian fritz circuit? Am I reading the spec right that its accurate for +/- 2mv or what does the +2d mean?
Yes, your DMM is good enough. You can use the 500mV range so you will have 10uV resolution. The 2d in the spec means 2 digits so the error can be 0.03% of the measured value plus 20uV in this case.

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Post by White noiz » Wed Nov 07, 2018 1:10 pm

Hi guys, I'm new here and also a total noob when it comes to electronics. At the moment all I am making is hot components!!!! :bang:

So, I'm trying to build the transistor matcher by Ian Fritz in the layout of rogloks build at the start of the thread. One problem though is that my diodes glow and then dim. Haha. My build looks the same as rogloks on the top, but do I need to cut the circuit in places underneath with a drill as well as the 2 resistors?

EDIT: OK I screwed up. I needed to properly cut the stripboard properly under the 3.9k resistors and under the ic on the emitter strips!! :doh:
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Last edited by White noiz on Thu Nov 08, 2018 10:58 am, edited 1 time in total.

aabbcc
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Post by aabbcc » Wed Nov 07, 2018 8:21 pm

Synthiq wrote:
aabbcc wrote:Quick question, is my DVM up to par for selecting transistors with no more than 2mv difference using the ian fritz circuit? Am I reading the spec right that its accurate for +/- 2mv or what does the +2d mean?
Yes, your DMM is good enough. You can use the 500mV range so you will have 10uV resolution. The 2d in the spec means 2 digits so the error can be 0.03% of the measured value plus 20uV in this case.
Thanks! Measured 100x bc547 and 557 from taped rolls (fairchild/on semi). None deviated more than 1.85 mV against the transistor I was measuring againstl. Also adding a pc chassis fan made a huge difference in stabilizing them to get a stable voltage reading.

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phisynth
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Post by phisynth » Thu Nov 08, 2018 5:34 pm

aabbcc wrote:Also adding a pc chassis fan made a huge difference in stabilizing them to get a stable voltage reading.
Indeed, I noticed that too. Here's what I did with mine :

Image

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Kevin Mitchell
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Post by Kevin Mitchell » Wed Dec 26, 2018 8:57 am

I've designed my own layout for the MFOS circuit. Works like a charm. Let me know if you build your own! You could translate the layout for vero board if that's your style.

Transfer PDF here
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Image

synthpriest
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Post by synthpriest » Wed Dec 26, 2018 3:22 pm

Thanks to everyone for all the enlightening posts in this thread. Will give the circuit a go during the next days. :hyper:

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Grumble
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Post by Grumble » Sun Jan 06, 2019 4:29 am

Image

Just soldered this on a perfboard and started measuring.
I selected transistors for a ladder filter in pairs that are less than 2mV apart.
Is that close enough?

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phisynth
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Post by phisynth » Sun Jan 06, 2019 9:40 am

Yes

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Grumble
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Post by Grumble » Sun Jan 06, 2019 9:55 am

:hihi: :rock:

Caesar56
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Post by Caesar56 » Wed Jan 09, 2019 1:44 am

analogdata wrote:I have three pcbs left made from the files found on midisizer.
Image

Image

$6+postage
(Also have the needed LM 4040 if you want it as well. $1,5 a piece)

Will be sent from Sweden.

Pm if interested.

:bananaguitar:
VERY interested in this. Looks spot on. :nana:

skautkurt
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Post by skautkurt » Thu Feb 14, 2019 10:52 am

Hi People,

I build the npn-part of the Ian Fritz tester, and tried matching some bc547s with it. It seems to work, but the values don't really stabilise. They always wander around, even moving closer or further away changes the drastically. I have a fan pointing toward both transistors, and I am leaving one in place as a reference.
I have the sneaking suspicion that the multimeter I am using is not up to sniff (UNI-T UT61E). On the V setting it shows 4 places after the decimal point.

Any input? I really want to finish my Filter (Kassus Transistor Ladder PCB (Thanks Kassu, really nice boardqualitiy and good layout, btw :)))

Thanks

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emmaker
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Post by emmaker » Thu Feb 14, 2019 11:25 am

skautkurt wrote:Hi People,

I build the npn-part of the Ian Fritz tester, and tried matching some bc547s with it. It seems to work, but the values don't really stabilise. They always wander around, even moving closer or further away changes the drastically. I have a fan pointing toward both transistors, and I am leaving one in place as a reference.
I have the sneaking suspicion that the multimeter I am using is not up to sniff (UNI-T UT61E). On the V setting it shows 4 places after the decimal point.

Any input? I really want to finish my Filter (Kassus Transistor Ladder PCB (Thanks Kassu, really nice boardqualitiy and good layout, btw :)))

Thanks
The transistors are extremely sensitive to temperature changes. I wouldn't use a fan to blow air over them. Reason is that even though the volume of air going over the transistors is going to stabilize the temperature somewhat there could be changes in that air's temperature going into the fan. I think that you'd be better to insulate the transistors so you have no air movement. I have a rag or box I put over the testing circuit and let it stabilize before I take readings.

skautkurt
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Post by skautkurt » Thu Feb 14, 2019 2:36 pm

emmaker wrote: The transistors are extremely sensitive to temperature changes. I wouldn't use a fan to blow air over them. Reason is that even though the volume of air going over the transistors is going to stabilize the temperature somewhat there could be changes in that air's temperature going into the fan. I think that you'd be better to insulate the transistors so you have no air movement. I have a rag or box I put over the testing circuit and let it stabilize before I take readings.
Okay, I will try putting the whole circuit under/inside a box tomorrow, and we'll see what happens. Thanks for the input.
cheers

skautkurt
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Post by skautkurt » Fri Feb 15, 2019 10:27 am

I think I am too stupid for this...when I move away from the box that contains the circuit (normally I am sitting like half a meter away from it), so further than normally (a meter or so) values shown on the multimeter change drastically (3-5mV), and if I move closer, it jumps back to the old values...
Any Ideas? Or are the measurements this sensitive? How is one supposed to get stable and matched values like this??? :bang:

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fuzzbass
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Post by fuzzbass » Fri Feb 15, 2019 11:17 am

skautkurt wrote:I think I am too stupid for this...when I move away from the box that contains the circuit (normally I am sitting like half a meter away from it), so further than normally (a meter or so) values shown on the multimeter change drastically (3-5mV), and if I move closer, it jumps back to the old values...
Any Ideas? Or are the measurements this sensitive? How is one supposed to get stable and matched values like this??? :bang:
You just have an unusually strong aura. :zen:

If it was your body heat, and not from contact with either transistor, it would show up in both of them at the same time. You don't need a box. A fan helps. So do plastic tweezers for handling the parts. My little matching rig (Fritz method, built on stripboard) has a ziff socket so I can drop the parts in with tweezers, and clamp them with the little lever. If you can keep your fingers off the transistors between resting and testing, things speed up a lot. I also use an hfe tester to rough sort them, which results in fewer tests per match.
Wired for weird

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tobb
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Post by tobb » Fri Feb 15, 2019 11:22 am

emmaker wrote:
The transistors are extremely sensitive to temperature changes. I wouldn't use a fan to blow air over them. Reason is that even though the volume of air going over the transistors is going to stabilize the temperature somewhat there could be changes in that air's temperature going into the fan. I think that you'd be better to insulate the transistors so you have no air movement. I have a rag or box I put over the testing circuit and let it stabilize before I take readings.
best is to put ARMAFLEX isolation on top of them.

Its special isolation used for ice/hot-water installations,you can buy it also in tape form,its an elastomerfoam.

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