The bench in Sparky's Lab is cleared off and ready for the Keysight SMU.
The mission is to match some J113 Jfets to see how they perform in the Pearl 3. The first thing is to select a tight group of 4ma ish Idss J113 Jfets. The expectation is that the J113 transconductance will be close to the 2SK209 providing similar gain. Also expected is the noise will be more than the 2SK170 and perhaps not a lot more than the 2SK209.
With that said my Impression that the noise from the connected cartridge and 47k resistor will far exceed the minimized P 3 circuit even with the the J113 installed. I do not know, we will see.
While the SMU is on the bench I will trace some PNP transistors including the ZTX457 and ZTX541.
Thanks DT
The mission is to match some J113 Jfets to see how they perform in the Pearl 3. The first thing is to select a tight group of 4ma ish Idss J113 Jfets. The expectation is that the J113 transconductance will be close to the 2SK209 providing similar gain. Also expected is the noise will be more than the 2SK170 and perhaps not a lot more than the 2SK209.
With that said my Impression that the noise from the connected cartridge and 47k resistor will far exceed the minimized P 3 circuit even with the the J113 installed. I do not know, we will see.
While the SMU is on the bench I will trace some PNP transistors including the ZTX457 and ZTX541.
Thanks DT
All about Q
All around the number eight - it should be a low-noise and low-impedance voltage source for the discrete input amplifier. And that's exactly what it / she does.
In fact, any low-frequency small-signal transistor is suitable at this point. That's why I would have liked a detailed statement from Jim - and Drew too.
All around the number eight - it should be a low-noise and low-impedance voltage source for the discrete input amplifier. And that's exactly what it / she does.
In fact, any low-frequency small-signal transistor is suitable at this point. That's why I would have liked a detailed statement from Jim - and Drew too.
I'm really sorry, but I can do absolutely nothing with this posting. What are you trying to say?
No offense,
HBt.
Now I see what you're up to, you want to replace Q1 to Q4 with J113 switches - great idea, but only if the procedure or the search for the appropriate and correct dimensioning of a source circuit with negative feedback comes out later. Everything else is just a bit of playing around.
The EQ Pearl 3 circuit is not a playground. The thing has a specific task to fulfill.
But go ahead and do it, you never know what will come of it.
😱
System
What other analyzers do you use?
Regards,
HBt.
The EQ Pearl 3 circuit is not a playground. The thing has a specific task to fulfill.
But go ahead and do it, you never know what will come of it.
😱
System
What other analyzers do you use?
Regards,
HBt.
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To paraphrase "Treasure of the Sierra Madre": "Data, we don't need no stinkin data". How did the committee react when you opened your thesis defense with that statement?
This is getting terribly OT, but to put it to rest -- the harmonics of a 1mV signal injected into the error amplifier of several regulators. For good measure, Zout of poz regulators too.
Attachments
Hello, All; I recently got a kit and am anxiously awaiting its arrival. I thought I would look into enclosure options and look at the custom ones from Modushop, which seem expensive to me . I know there are two Hammond enclosures mentioned in the build notes, and I was wondering if anyone had experience with the build using these enclosures...
Thanks in advance
Thanks in advance
So' buying a complete kit is really a wise decision.
I've spent the last few hours selecting suitable jFets (unfortunately there are only BL-Grade for sale here locally; are they still Toshiba originals? they're not cheap!) And indeed, I have found two almost exact pairs of four (eight in total Q1234). But 1 in 18 is at the end of the spectrum in each case, too far away from the center of the distribution of the quantity.
So, I'll get started and take a closer look at the P3's input stage. But with Vcc=14.3V and R1=750Ohm, it's not going to work.
Let's see how the OPs perform here in terms of measurements, I'm very curious to see if even a 741 does its job well enough - just for fun, of course.
Bye,
HBt.
I've spent the last few hours selecting suitable jFets (unfortunately there are only BL-Grade for sale here locally; are they still Toshiba originals? they're not cheap!) And indeed, I have found two almost exact pairs of four (eight in total Q1234). But 1 in 18 is at the end of the spectrum in each case, too far away from the center of the distribution of the quantity.
So, I'll get started and take a closer look at the P3's input stage. But with Vcc=14.3V and R1=750Ohm, it's not going to work.
Let's see how the OPs perform here in terms of measurements, I'm very curious to see if even a 741 does its job well enough - just for fun, of course.
Bye,
HBt.
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Hello hbtaudio,
if you would like to order from Mouser Germany, Munich, you could get 100 Toshiba 2SK209GR at a price of
25,20 € (100% originals!).
https://www.mouser.de/ProductDetail/Toshiba/2SK209-GRTE85LF?qs=8TQFHmocP6xDVEMkPbnGBw==
You could find some other parts needed to build the PEARL 3 to get over the 50 € to get the benefit of free
delivery.
I needed around 30 TOSHIBA 2SK209GR off the role to get a very, very closely matched octett.
Greets
Dirk
if you would like to order from Mouser Germany, Munich, you could get 100 Toshiba 2SK209GR at a price of
25,20 € (100% originals!).
https://www.mouser.de/ProductDetail/Toshiba/2SK209-GRTE85LF?qs=8TQFHmocP6xDVEMkPbnGBw==
You could find some other parts needed to build the PEARL 3 to get over the 50 € to get the benefit of free
delivery.
I needed around 30 TOSHIBA 2SK209GR off the role to get a very, very closely matched octett.
Greets
Dirk
Cap multiplier choice of ZTX457 in lieu of 851, see posts #291 and #581.
ZTX457 has a better Vearly than the 851, and so was chosen for the capacitor multiplier position, and the 457 has significantly better availability than the 851, which in no less than two instances for this project I bought the last of the stock available in N.America! Stock is wildly variable and very small quantity with ZTX851.
Substitution of 457 in that position quite simply allowed more kits to be made.
ZTX457 has a better Vearly than the 851, and so was chosen for the capacitor multiplier position, and the 457 has significantly better availability than the 851, which in no less than two instances for this project I bought the last of the stock available in N.America! Stock is wildly variable and very small quantity with ZTX851.
Substitution of 457 in that position quite simply allowed more kits to be made.
Hahaha, touche my good fellow, touche. But this isn't a thesis defense, it's a casual chat. The stakes, and the investment in personal time I'm able to make are not comparable.
Yes, this is getting OT, but it seems we're talking about two different things. I'm not disputing the output impedance of a better regulator. I'm talking about where the load current goes.
Anyway, I was mostly pointing out that the humble 78xx / 79xx regulators may not have the lowest output Z, but they do have other virtues. Some of which may be relevant in this application. IMHO they are not a bad choice at all.
What I am saying is: "Let us see the data".
Not directed at you, but the "we don't need data" person.
Thanks
DT
Respectfully, I stand by my statement that no data is needed to understand the basic theory.
Did you go through college ignoring everything in the textbooks because it was all theory presented with few, if any, measurements? No, of course not.
Asking for data "or it isn't real" (tacit implication) could be interpreted as a cheap shot at someone's credibility. But I'm not here to quarrel or be offended, and will happily give you the benefit of the doubt. Heaven knows I've stuffed my own foot in my mouth on the internet a few times.
FWIW, I deal regularly with switching and linear regulators, and associated PDNs in my day job. I have seen and made countless power supply measurements in my career, all of which are the intellectual property of my employer. So I will suffer the handicap of being unable to share what data I do have at hand. Perhaps when I retire I will have time to entertain such frivolous requests (don't count on it).
Did you go through college ignoring everything in the textbooks because it was all theory presented with few, if any, measurements? No, of course not.
Asking for data "or it isn't real" (tacit implication) could be interpreted as a cheap shot at someone's credibility. But I'm not here to quarrel or be offended, and will happily give you the benefit of the doubt. Heaven knows I've stuffed my own foot in my mouth on the internet a few times.
FWIW, I deal regularly with switching and linear regulators, and associated PDNs in my day job. I have seen and made countless power supply measurements in my career, all of which are the intellectual property of my employer. So I will suffer the handicap of being unable to share what data I do have at hand. Perhaps when I retire I will have time to entertain such frivolous requests (don't count on it).
I'll offer a simple reframing, just as food for thought, and will end the OT tangent here...
Time domain: How does a load current transient appear at the input side of the regulator?
Frequency domain: What frequency content in the load current appears on the input side of the regulator?
The regulator acts as a filter between the load and unregulated power source.
Draw your own conclusions, and by all means, hook up a scope and quantify things if you like - yes, it will enhance your understanding.
Time domain: How does a load current transient appear at the input side of the regulator?
Frequency domain: What frequency content in the load current appears on the input side of the regulator?
The regulator acts as a filter between the load and unregulated power source.
Draw your own conclusions, and by all means, hook up a scope and quantify things if you like - yes, it will enhance your understanding.
If that were true it would show up in the measurements.
You have stepped in it now.
Claiming high frequency junk back to the input rail is not basic theory.
You need to back that one up with some evidence.
Thanks DT
For a standard series regulator topology, there are only two places load current can go:
Have I missed something?
- through the shunt elements (decoupling cap) back to local ground
- through the regulator pass transistor back to the input rail
Have I missed something?
Yes, evidence that there is a problem that requires fixing.
I have found the ignore button
@hifiZen This discussion, while maybe useful, has gone severely off topic for the P3. It would likely be great in the power supply forum. https://www.diyaudio.com/community/forums/power-supplies.67/
