fdegrove said:
Why should I be taken less seriously? Just because I didn't tack on a gate stopper and clamping diodes to appease Fred?
I just copy the text from the original post and paste it. And usually italicize it. Though if I'm quoting within my own text, I'll just use quotation marks.
Nope. When you give a quote, the quote should only contain that which was said by the person you're quoting.
se
Hi,
ROTLMAO...
Wake up...the second line in the quote was never posted by me or am I daydreaming???
And of course it does but not in this case, it's editable anyway...can you point me to the original text?
I'm sure I never wrote anything like the second phrase...or maybe you made a single quote out of two different posts...I just hope no one else follows that practice....
Cheers,
ROTLMAO...
Wake up...the second line in the quote was never posted by me or am I daydreaming???
And of course it does but not in this case, it's editable anyway...can you point me to the original text?
I'm sure I never wrote anything like the second phrase...or maybe you made a single quote out of two different posts...I just hope no one else follows that practice....
Cheers,
fdegrove said:
Wake up? Why don't you just say what the hell you mean instead being so abstruse and taking these back door approaches and expecting me to figure out what you're trying to say?
You know, something simple and straightforward like "Steve, the second line in the quote was never posted by me or am I daydreaming???" Is that too difficult for you? it's like your saying "When is a man made of wood?" instead of saying "Hey Steve, hand me that ruler."
I thought you were asking how to quote from someone else's message seeing as I'd just quoted Fuling.
And of course it does but not in this case, it's editable anyway...can you point me to the original text?
I'm sure I never wrote anything like the second phrase...or maybe you made a single quote out of two different posts...I just hope no one else follows that practice....
It wasn't your quote. The second line was my reply to your quote of the first line. Apparently I forgot to put the end quote at the end of your line before I replied, then stepped away from the computer, came back and tacked the end quote on to the end of the whole thing and then replied again.
My apologies.
Re: more than anyone wants to know
Well, they're a transient so they do have high frequency components just as any transient. But the risetime is finite. For example, the charge coming off your finger during an ESD event is going through roughly the equivalent of 100pF in series with 1.5k ohms. So while there will be high frequency content simply due to its transient nature (even a single cycle of a sinewave has frequency content above the period of the sine) but the bulk of the energy isn't going to be up in the RF range. Though I suppose if you electrostatically charge an isolated metallic object and discharge it you could really yank up the risetime.
Yes. With the distinction that the node between the two capacitances (the shield) is tied to ground which significantly reduces capacitive coupling. That's how Faraday shielding works.
To some degree, sure. But we're talking about just four parts here. You'd almost have to try to get the shield lead much longer than an inch or so.
Yet all that it did was reset the CMOS logic. You've been talking about blowing up power MOSFETs.
And I'm not going to say it would be absolutely impossible to blow the MOSFET with a nasty electrostatic discharge. But I seem to be in fairly good company in feeling that it's not the huge risk that you've been making it out to be.
Again, look at the Son of Zen. The only thing between the MOSFET gates and the inputs is a 221 ohm resistor so they're not even afforded the isolation that a transformer would.
And I'm not saying your concern is wholly unwarranted. I'd just like to know why you've singled me out.
The lumped elements are just fine for the normal operating frequencies as well as at the resonant frequency of the system. Again, distributed element analysis doesn't come into play until the wavelengths involved are on the order of the size of the system. And there's simply not going to be any RF interference in the system of any magnitude sufficient to go blowing holes in the MOSFETs.
The unloaded resonant frequency of the 13K7-A is 120kHz. Add the gate capacitance and it gets lower still.
Remember, your original concern had nothing to do with ESD but rather the simple resonance of the transformer causing overshoot sufficient to blow the MOSFET.
ESD's a different matter because you're dealing with thousands of volts.
How is simply having several 10s of volts at the gate of the MOSFET any sort of inherent problem in a source follower? I can see it being a problem with a common source circuit. But this isn't a common source circuit.
Perhaps with the pulse transformers that you seem to be familiar with. But an audio transformer isn't a pulse transformer. Again, the unloaded resonant frequency of the 13K7-A is 120kHz. Adding the input capacitance of the MOSFET will only make it lower.
Except that the resonant frequency here isn't at those frequencies.
Here are the bare facts. Actual measurement of the 13K7-A unloaded. The MOSFET input capacitance will effectively be in parallel with the 13K7-A's secondary. Please explain to me how that additional capacitance will increase the resonant frequency.
se
Fred Dieckmann said:
Well, they're a transient so they do have high frequency components just as any transient. But the risetime is finite. For example, the charge coming off your finger during an ESD event is going through roughly the equivalent of 100pF in series with 1.5k ohms. So while there will be high frequency content simply due to its transient nature (even a single cycle of a sinewave has frequency content above the period of the sine) but the bulk of the energy isn't going to be up in the RF range. Though I suppose if you electrostatically charge an isolated metallic object and discharge it you could really yank up the risetime.
Yes. With the distinction that the node between the two capacitances (the shield) is tied to ground which significantly reduces capacitive coupling. That's how Faraday shielding works.
To some degree, sure. But we're talking about just four parts here. You'd almost have to try to get the shield lead much longer than an inch or so.
Yet all that it did was reset the CMOS logic. You've been talking about blowing up power MOSFETs.
And I'm not going to say it would be absolutely impossible to blow the MOSFET with a nasty electrostatic discharge. But I seem to be in fairly good company in feeling that it's not the huge risk that you've been making it out to be.
Again, look at the Son of Zen. The only thing between the MOSFET gates and the inputs is a 221 ohm resistor so they're not even afforded the isolation that a transformer would.
And I'm not saying your concern is wholly unwarranted. I'd just like to know why you've singled me out.
The lumped elements are just fine for the normal operating frequencies as well as at the resonant frequency of the system. Again, distributed element analysis doesn't come into play until the wavelengths involved are on the order of the size of the system. And there's simply not going to be any RF interference in the system of any magnitude sufficient to go blowing holes in the MOSFETs.
The unloaded resonant frequency of the 13K7-A is 120kHz. Add the gate capacitance and it gets lower still.
Remember, your original concern had nothing to do with ESD but rather the simple resonance of the transformer causing overshoot sufficient to blow the MOSFET.
ESD's a different matter because you're dealing with thousands of volts.
How is simply having several 10s of volts at the gate of the MOSFET any sort of inherent problem in a source follower? I can see it being a problem with a common source circuit. But this isn't a common source circuit.
Perhaps with the pulse transformers that you seem to be familiar with. But an audio transformer isn't a pulse transformer. Again, the unloaded resonant frequency of the 13K7-A is 120kHz. Adding the input capacitance of the MOSFET will only make it lower.
Except that the resonant frequency here isn't at those frequencies.
Here are the bare facts. Actual measurement of the 13K7-A unloaded. The MOSFET input capacitance will effectively be in parallel with the 13K7-A's secondary. Please explain to me how that additional capacitance will increase the resonant frequency.
se
Attachments
Hi Fred, I presume that you have been through this before. The situation to me seems that it would be a good idea to protect gate of the mosfet with a zener. This is because an input transformer can resonate at ultrasonic frequencies, and with its extra gain as well, can in theory, punch through the gate. It is just good engineering practice to do so.
Fred, I know that you have stated this every which way, but I think that others reading this thread are getting confused for the 'trees' rather than looking at the 'forest'. Folks, that is all there is to it.
Now, the stopper resistor is another question. I ALWAYS use a stopper resistor with my mosfets, and sometimes even in the base of any bipolar output transistors. This is also just good engineering practice, but for certain RF designs, this stopper resistor could be a problem. There are more exotic alternatives, but a resistor is pretty darn cheap and easy to do.
Why don't we go on from here?
Fred, I know that you have stated this every which way, but I think that others reading this thread are getting confused for the 'trees' rather than looking at the 'forest'. Folks, that is all there is to it.
Now, the stopper resistor is another question. I ALWAYS use a stopper resistor with my mosfets, and sometimes even in the base of any bipolar output transistors. This is also just good engineering practice, but for certain RF designs, this stopper resistor could be a problem. There are more exotic alternatives, but a resistor is pretty darn cheap and easy to do.
Why don't we go on from here?
john curl said:
Well here's the thing, John. I can see how that can easily happen with a common source circuit. Your gate-to-source voltage is effectively your input voltage so if your input voltage exceeds the gate-to-source breakdown voltage, you can punch a hole through the gate.
But explain to me how you would have this situation in a common drain circuit. It's a source follower. So the output is taken from the source. And since in a source follower your output voltage is effectively your input voltage, and the output is non-inverting so that the voltage at the gate is of the same polarity as the source, the voltage difference between the gate and the source is effectively going to be zero.
In other words, if your gate is at say +5 volts, your source is going to be at +5 volts. So the voltage between gate and source will be (+5) - (+5) = 0.
se
What the h*** is "passive voltage gain"?
What?..........we have a New Age think-speak word for "step-up transformer".
Glad to see that Phred (and I) aren't the only ones here who believe in gate dampers.....or zener clamps.
Yes, it will probably work ok without them. Until some very expensive drivers get ruined when things go wrong. Don't say that no one warned you.
Jocko
What?..........we have a New Age think-speak word for "step-up transformer".
Glad to see that Phred (and I) aren't the only ones here who believe in gate dampers.....or zener clamps.
Yes, it will probably work ok without them. Until some very expensive drivers get ruined when things go wrong. Don't say that no one warned you.
Jocko
Right on, Jocko. I don't know you, but I think we share the same attitude. For the record, it is more difficult for a fet follower to develop enough gate voltage to break it, because the input follows the output. BUT, if the output was at very low impedance (like my WATT 1's are at 2KHz) and the input was very high, then the gate could be breached in an instant. Probable? Maybe not, but it is prudent to cover all bases. How about those Pintos that exploded in a rear end collision? $10 could have covered the extra cost to prevent it, but the engineers decided it wasn't worth the effort. Same thing here.
Re: What the h*** is "passive voltage gain"?
Nope. I use step-up transformer for step-up transformer and passive voltage gain simply to distinguish it from active voltage gain.
I believe in damping too. Just that I see sufficient damping inherent in the transformer. And if there's sufficient damping inherent in the transformer, why add a resistor?
And I don't think clamps are necessarily a bad idea. Just don't see the absolute necessity that Fred does.
And still don't understand why this circuit is the ONLY one that's been singled out for baggin on about clamping diodes out of all the other circuits posted in this thread which do not include them.
How you going to ruin any drivers? This isn't a design that lends itself to high output power and the output is capacitively coupled.
se
Jocko Homo said:
Nope. I use step-up transformer for step-up transformer and passive voltage gain simply to distinguish it from active voltage gain.
I believe in damping too. Just that I see sufficient damping inherent in the transformer. And if there's sufficient damping inherent in the transformer, why add a resistor?
And I don't think clamps are necessarily a bad idea. Just don't see the absolute necessity that Fred does.
And still don't understand why this circuit is the ONLY one that's been singled out for baggin on about clamping diodes out of all the other circuits posted in this thread which do not include them.
How you going to ruin any drivers? This isn't a design that lends itself to high output power and the output is capacitively coupled.
se
john curl said:
Odd. That was pretty much my argument when I've recommended people not defeat the safety grounds on their equipment and have been critical of those who recommend that they do. Yet "prudent" wasn't the word you used to describe my concern on that matter.
So it's prudent to cover all bases to prevent blowing a MOSFET but it's not prudent to cover all bases to prevent electrocution.
Hmmm...
se
SOS, different day.......
Steve,
I spent weeks on ESD testing and reading the literature on what an actual ESD waveform looks like. But you can make a couple of assumptions off the top of your head and decide I can't be right. OK........
You want to argue topics that 3 different engineers with experience working with electronics of about 25 to 30 years each are in concurrence on. A mystery to me.......
I know you are not stupid since I have seen you make logical arguments and deductions on many occasions. Nobody could be egotistical enough to assume he knows more than several very qualified individuals (on this and many other topics) for so many subjects. I can think of only one other explanation.
I feel pretty guilty for arguing (and complaining about here and behind the scenes) with someone who I honestly think is not well. The problem is that these battles effect the whole tone and reflect on the credibility of the whole forum. I don't even want to talk about the behind the scenes comments that go on.
To everybody else,
Since this seems to be a constantly repeating situation that can't be fun or beneficial for Mr. Eddy, and seems to provoke anger and frustration for any number of people who get sucked into these storms, I think the moderators need to think real hard about how to do something about this. People are going to see little point in correcting errors and expanding the scope of discussions if the are going to end in a ****ing contest as often as not. I just wonder what these episodes bring to the forum?
The novelty of the fights wore off long ago, and I don't know of anybody who enjoys them anymore. Why are the mistakes, arguments, insults, and desperate face saving diatribes of one individual, as important as the inputs of several people to straighten it out each time? Does this educate anybody about audio design? Is it entertaining? I wonder who will get tired of it enough to leave when mistakes are constantly posted, and they have to take a beating each time they try to correct them. Are the laws of physics, the equations describing electrical engineering, and references by mathematics and engineers on the web and in textbooks just matters of opinion? Do they carry no more weight than the pronouncements of one guy, who has been wrong on many occasions and seems to have no desire to learn from his mistakes?
Steve,
I spent weeks on ESD testing and reading the literature on what an actual ESD waveform looks like. But you can make a couple of assumptions off the top of your head and decide I can't be right. OK........
You want to argue topics that 3 different engineers with experience working with electronics of about 25 to 30 years each are in concurrence on. A mystery to me.......
I know you are not stupid since I have seen you make logical arguments and deductions on many occasions. Nobody could be egotistical enough to assume he knows more than several very qualified individuals (on this and many other topics) for so many subjects. I can think of only one other explanation.
I feel pretty guilty for arguing (and complaining about here and behind the scenes) with someone who I honestly think is not well. The problem is that these battles effect the whole tone and reflect on the credibility of the whole forum. I don't even want to talk about the behind the scenes comments that go on.
To everybody else,
Since this seems to be a constantly repeating situation that can't be fun or beneficial for Mr. Eddy, and seems to provoke anger and frustration for any number of people who get sucked into these storms, I think the moderators need to think real hard about how to do something about this. People are going to see little point in correcting errors and expanding the scope of discussions if the are going to end in a ****ing contest as often as not. I just wonder what these episodes bring to the forum?
The novelty of the fights wore off long ago, and I don't know of anybody who enjoys them anymore. Why are the mistakes, arguments, insults, and desperate face saving diatribes of one individual, as important as the inputs of several people to straighten it out each time? Does this educate anybody about audio design? Is it entertaining? I wonder who will get tired of it enough to leave when mistakes are constantly posted, and they have to take a beating each time they try to correct them. Are the laws of physics, the equations describing electrical engineering, and references by mathematics and engineers on the web and in textbooks just matters of opinion? Do they carry no more weight than the pronouncements of one guy, who has been wrong on many occasions and seems to have no desire to learn from his mistakes?
Steve Eddy said:
To Fred Dieckman:
Fred, I don't get your problem that led to your last post to "everybody". I looked back to SE's posts on the last couple of pages, and they seem reasonable. For example, the one quoted here. Not agreeing with you, but a straight technical argument. (Not that I agree with it fully, but that's not the point, is it?)
What's the problem? If you and SE can't get along, I would say you both should solve it. Don't try to enlist the rest of the forum in your little war.
Jan Didden
just a anotther matter of opinion
I would agree if I thought it was just me. I get constant Email indicating that that is not the case. There are others that have been in the middle of the same nonsense with the same person over the same issues.
I have bent over backwards supplying technical information from reputable sources (as have others) only to be dragged into the same recriminations, abuse, and cries of "it is really a matter of opinion." On occasions it is a matter of opinion and that's fine. When it is lazy speculation (as is so often) that flies in the face of knowledge of people that have been in an industry for twenty years and go through the trouble to find links with further detail on a subject, it is a much different matter. I realize that not everybody understands the issues in a technical discussion. Mr. Eddy plays on that like it was a violin. If no one really cares when they are being "had" (for reasons that are a mystery to me) then anyone's efforts to actually tell the truth and educate are in vain. Perhaps he holds all of us in contempt and making up stuff and attacking anyone who tries to call him on it, is his way of expressing this. Your guess is as good as mine.......
I would agree if I thought it was just me. I get constant Email indicating that that is not the case. There are others that have been in the middle of the same nonsense with the same person over the same issues.
I have bent over backwards supplying technical information from reputable sources (as have others) only to be dragged into the same recriminations, abuse, and cries of "it is really a matter of opinion." On occasions it is a matter of opinion and that's fine. When it is lazy speculation (as is so often) that flies in the face of knowledge of people that have been in an industry for twenty years and go through the trouble to find links with further detail on a subject, it is a much different matter. I realize that not everybody understands the issues in a technical discussion. Mr. Eddy plays on that like it was a violin. If no one really cares when they are being "had" (for reasons that are a mystery to me) then anyone's efforts to actually tell the truth and educate are in vain. Perhaps he holds all of us in contempt and making up stuff and attacking anyone who tries to call him on it, is his way of expressing this. Your guess is as good as mine.......
Re: SOS, different day.......
I'm not saying you can't possibly be right. I'm simply saying that you're blowing this out of all proportion simply because I happened to be the one to post the schematic.
And while I admit that some of my arguments were the result of defensiveness on my part, they've only been in response to the offensiveness initiated on your part.
So I'll leave this here by asking yet again a question which you have so far refused to answer:
Why did you not say a word about the half dozen other schematics posted in this thread which also did not include clamping diodes?
se
Fred Dieckmann said:
I'm not saying you can't possibly be right. I'm simply saying that you're blowing this out of all proportion simply because I happened to be the one to post the schematic.
And while I admit that some of my arguments were the result of defensiveness on my part, they've only been in response to the offensiveness initiated on your part.
So I'll leave this here by asking yet again a question which you have so far refused to answer:
Why did you not say a word about the half dozen other schematics posted in this thread which also did not include clamping diodes?
se
till said:
Tsk tsk tsk.
http://www.diyaudio.com/forums/showthread.php?postid=212528#post212528
You just wait 'til your father gets home young man. He's gonna open up a can of Whoop *** on you.
se
You know why i dont want him to tell me at the ? there should be zehners... Thats the only thing i would be able to draw there by my shelf.
i admit i don´t know anything, not about ESD, not about clamping diodes etc.
I´m even not able to draw any schematic.
If Fred wants to give a comment, please Fred, post a working schematic with all kind of ESD protection and clamping needed to feel well.
Else i better wait for Nelsons Zen variation, and build some lightbulb Zens until then...
i admit i don´t know anything, not about ESD, not about clamping diodes etc.
I´m even not able to draw any schematic.
If Fred wants to give a comment, please Fred, post a working schematic with all kind of ESD protection and clamping needed to feel well.
Else i better wait for Nelsons Zen variation, and build some lightbulb Zens until then...
Hi @all,
I've made some calculations if a shieled transformer prevents the MOSFET of breakdown or not. This is not made for Steve or Fred, just for me and all the others who are interested in.
Let's start with the Jensen transformer 13k7a. I looked into the data sheet and found unfortunately not information about the pimary inductance. Very bad as starting point. Well, refering to the frequency response curve I can find a -3dB point at 0,9Hz when driven from a source impedance of 150 Ohms.
This results in a primary inductance of L = (150 Ohms + 15 Ohms) / (2 * pi * 0.9Hz) = 30H
The primary resistance is 15 Ohms and the capacitance from primary to shield is about 500pF.
When using an ESD-signal of 2kV with 100pF and 1,5k the 100pF and the input capacitor will give a 1:6 divider and a resulting capacitor of about 600pF together.
The primary inductance and the input capacitance will give an LC-resonator wich is ringing at f = 1 / (2 * pi * sqrt(L * C)) = 1,2kHz.
The elements are very similar to a crystal, high inductivity, moderate resistance and low capacitance so heavily ringing is expected. And I'm too lazy to calculate Q.
The input of the transformer is ringing at a voltage of 2kV * 100pF / (100pF + 500pF) = 330V. Transformed to the output there will be an output voltage of N * Vin = 1,6kV.
Of course the tranny saturates and I did not calculated any capacitance from the MOSFET to the LC resonator. And the calulations are not completely correct. But I'm astonished that the MOSFET will destroyed by this test at a quite low frequency at about 1kHz not at RF as I hat expected. And shielding does not help anything.
I've made some calculations if a shieled transformer prevents the MOSFET of breakdown or not. This is not made for Steve or Fred, just for me and all the others who are interested in.
Let's start with the Jensen transformer 13k7a. I looked into the data sheet and found unfortunately not information about the pimary inductance. Very bad as starting point. Well, refering to the frequency response curve I can find a -3dB point at 0,9Hz when driven from a source impedance of 150 Ohms.
This results in a primary inductance of L = (150 Ohms + 15 Ohms) / (2 * pi * 0.9Hz) = 30H
The primary resistance is 15 Ohms and the capacitance from primary to shield is about 500pF.
When using an ESD-signal of 2kV with 100pF and 1,5k the 100pF and the input capacitor will give a 1:6 divider and a resulting capacitor of about 600pF together.
The primary inductance and the input capacitance will give an LC-resonator wich is ringing at f = 1 / (2 * pi * sqrt(L * C)) = 1,2kHz.
The elements are very similar to a crystal, high inductivity, moderate resistance and low capacitance so heavily ringing is expected. And I'm too lazy to calculate Q.
The input of the transformer is ringing at a voltage of 2kV * 100pF / (100pF + 500pF) = 330V. Transformed to the output there will be an output voltage of N * Vin = 1,6kV.
Of course the tranny saturates and I did not calculated any capacitance from the MOSFET to the LC resonator. And the calulations are not completely correct. But I'm astonished that the MOSFET will destroyed by this test at a quite low frequency at about 1kHz not at RF as I hat expected. And shielding does not help anything.
Re: SOS, different day.......
Fred,
You pretty much answered yourself to all those questions and it seems to be right to the point. If you feel guilty about arguing, why don't you let it rest and see how the thread develops? It's been more than one member already asking you to stop, and it seems like you are fighting with windmills. The more you argue the deeper you go and less credibility you gain. I actually don't feel good about doing that, but somebody had to break the news to you, anyway.
ESD and whatever else you arguing about doesn't matter at all at this moment and at this stage of design. I don't even think that so many people will built that thing at all. So why are you such a nuisance and talk about it all the time, without providing any further useful input. If you want' to prove that SE is wrong (which I think you might have a hard time doing), do it somwhere else and give the guys who enjoy this thread a break.
I'm talking here as a moderator, and any of your subsequent posts with regard to Fred-SE argument will be moved to Texas. If you really insist, we will even open a special thread for that.
Fred Dieckmann said:
Fred,
You pretty much answered yourself to all those questions and it seems to be right to the point. If you feel guilty about arguing, why don't you let it rest and see how the thread develops? It's been more than one member already asking you to stop, and it seems like you are fighting with windmills. The more you argue the deeper you go and less credibility you gain. I actually don't feel good about doing that, but somebody had to break the news to you, anyway.
ESD and whatever else you arguing about doesn't matter at all at this moment and at this stage of design. I don't even think that so many people will built that thing at all. So why are you such a nuisance and talk about it all the time, without providing any further useful input. If you want' to prove that SE is wrong (which I think you might have a hard time doing), do it somwhere else and give the guys who enjoy this thread a break.
I'm talking here as a moderator, and any of your subsequent posts with regard to Fred-SE argument will be moved to Texas. If you really insist, we will even open a special thread for that.
Do not resuscitate
The secondary winding inductance is in parallel with impedance driving the primary
time the square of the turns ratio. The impedance driving the primary had better be very low for reasons already mentioned
winding capacitance and leakage inductance are distributed impedances and
a lumped element model will not tell you what is going on at RF.
Handbook of Transformer Design and Applications William Flanagan
http://www.amazon.com/exec/obidos/tg/detail/-/0070212910/002-3081024-0938420?vi=glance
I am going to start charging tuition.
Please this topic needs qualified emergency assistance! Is there a transformer designer in the house?
Or we could just let it lay on the floor and die. It is very old after all........
The secondary winding inductance is in parallel with impedance driving the primary
time the square of the turns ratio. The impedance driving the primary had better be very low for reasons already mentioned
winding capacitance and leakage inductance are distributed impedances and
a lumped element model will not tell you what is going on at RF.
Handbook of Transformer Design and Applications William Flanagan
http://www.amazon.com/exec/obidos/tg/detail/-/0070212910/002-3081024-0938420?vi=glance
I am going to start charging tuition.
Please this topic needs qualified emergency assistance! Is there a transformer designer in the house?
Or we could just let it lay on the floor and die. It is very old after all........
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