On a sunny day (Mon, 5 Jul 2010 05:30:03 -0500) it happened "Tim Williams" wrote in :
PK, great, well maybe that other poster has a point mentioning huge voltage peaks. I could imagine bottom of 102T spiking positive while left bottom connection of
300T spiking negative. Maybe you think that is damped by the other positive diodes, but then that 300T reverses the phase :-) If top left of 300T goes positive, then also bottom left of 300T will go negative. But I would check caps first.
You need to take differential measurments.
I plugged in some estimates based on an absouloute output voltage of
500V and they do indeed see 1.9KV.
You're an idiot. Usenet has always been that way. You not knowing that after all these years, shows everyone just how little attention you pay to the details.
The "that" which "you take", Jan, is the fact that you are an utter idiot where knowing about Usenet is concerned. You also lack skill in electronics.=A0 We already knew that, however. All the blank lines after your stupidity is more proof that you do not know anything about that which you blather on about. So, FOAD, Blather boy.
s up to the artistic capabilities of the creator of the posting to format t= he text anyway they want, in fact newsreaders who garble that text by refor= matting violate the principle of conservation of of creativity, so take tha= t.
It is not about "artisitic capabilities, you retarded twit. This is Usenet, a TEXT forum. There is no "artisit capability", IDIOT. There ARE, however, posting conventions and they have been around long before any dopey ditz like you ever claimed that they did not exist.. Grow up, idiot. If you want to include yourself, you shoul at least JOIN the community, not flip off every part of it that YOU don't like. You are an idiot, and so is the Williams dork.
heaters, fractional mA at -2kV, 100mA at +230V, 35mA at -230V). It runs cool and smooth for about a minute (aside from the snubbers, which get quite hot), then suddenly the output drops dead and the current limit starts squealing. One of the negative output diodes is failing shorted. (Good thing the current limit keeps it from nuking the transistors.)
the snubbers). The waveforms show 120V overshoot, which is well within ratings (1000V diode with about 600V peak reverse). I can't imagine it's an avalanche thing, as the reverse voltage is low and, until failure, the diodes run cool. I'm still more confused that it's consistently the negative side diode (three have died so far), which is the lighter loaded side.
Just FWIW: What you call stupid clics are often rather large and successful enterprises, the products of which even you will experience on a regular basis. Like when you are going places ...
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Nope. No capacitance values, no resistor values.
... oh well.
Did you scope the voltage at the transformer secondary? And the current into the diodes, with a current transformer?
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Is the part labeled "2 x 10mH 100mA 300T" causing problems when the +/-
250V outputs currents aren't balanced?-- I won't see Google Groups replies because I must filter them as spam
Well that's obviously wrong. The transformer only makes 300V peak = output (600p-p, not counting LL), and it's obviously full wave, not half = wave. The driver is clearly half bridge and the transformer ratio is = clearly 1:4+4.
Tim
--=20 Deep Friar: a very philosophical monk. Website:
Not even in the note that says "5.6k + 47pF"???
current
Voltage on both sides, yes. Current, no. I soppose recovery current = could be interesting; of course, that will be snubbed quite effectively = by leakage, so it will certainly be finite...
Hmm, I know the peak overshoot. I should be able to estimate peak = current from that, if I know LL and C. Meh, it'll probably be within =
50% of "it all comes from the primary", which isn't accurate enough to = estimate recovery.UF4007 is rated for 20-30A peak. They aren't heating up very much, at = least until failure. Do you think it could be peak current?
Tim
--=20 Deep Friar: a very philosophical monk. Website:
+/-
It doesn't seem to be. The waveforms on either end look identical and = inverted. The currents aren't aall that different. 30mA seems to be = enough to cause continuous conduction mode, so it's not trying to play = funny on that side.
Tim
--=20 Deep Friar: a very philosophical monk. Website:
Whoops, didn't see that, was looking in your text. And shouldn't it say snubbered, snubberated or snubberificated? :-)
Best to put them on the schematics. 47pF is almost nothing. Are you sure this quenches ringing enough?
That's for non-repetitive.
Possibly, because at 75nsec trr these are fairly slow. Since you probably don't want to spring for four of those Cree super thingamagics which would totally raid the beer kitty, why the 2x10mH common mode choke? Tried separate chokes yet?
Of course, if you came into a wad of cash:
BTW, for better schematics drawings you can use the free edition of Cadsoft Eagle, as long as it's hobby and not for profit use. Later when you want to buy it for business it's rather inexpensive. Not like Orcad.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
inverted. The currents aren't aall that different. 30mA seems to be enough to cause continuous conduction mode, so it's not trying to play funny on that side.
If the currents are unbalanced, you may need freewheeling rectifiers to ground, before the choke, on both sides.
RL
Ah, interesting.
The dead time voltages are near zero (give or take a small amount of = squiggle), so it seems to be okay.
Tim
--=20 Deep Friar: a very philosophical monk. Website:
============================================ But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, ?You fool!? will be liable to the hell of fire.
Matthew 5:22
============================================
father mike
============================================ But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, ?You fool!? will be liable to the hell of fire.
Matthew 5:22
============================================
father mike
sure
Yes, it gets hardly a cycle before the ringing is too weak to see.
Slow!? Come on, I know you love dabbling with MHz stuff, but gimme a = break, this is only 120k after all!
thingamagics
Hmm, "common mode" is a funny way to put it. The negative rail is = inverted, so I guess it should be "differential mode".
I used that since everyone else uses multiwinding chokes in forward = converters. Two chokes would take up more space and be more trouble to = wind; this is only one part.
I'm not buying them and I'm not mass-producing them, so don't bother = going all Joerg on me. ;-)
With 45pF at 200V (probably with high Q), I'll need even bigger = snubbers. The transistors might not appreciate trying to push around = the 455pF "not-recovery" capacitance, either. Actually, 28nC charge is = like 0.5A * 50ns reverse recovery, so they'd be just as bad! The only = difference is, you get the capacitance back each time, whereas the = reverse recovery is heat each time.
Anyway, even peak Irr were 0.5A, that's roughly 75ns * 0.5A * 4 diodes * =
120kHz * 2/cycle =3D 36mA effective reverse leakage. At 250V, that's = 9W, or 2.25W/diode, but recovery occurs at a few volts, not all 250, so = the real power is something else. Evidently it's fairly small, because = the diodes don't seem to heat up until the one dies...No one makes 1A SiC rectifiers? What's up with that?
Tim
--=20 Deep Friar: a very philosophical monk. Website:
Constantly repeating what your Father called you isn't helping at all.
============================================ But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, ?You fool!? will be liable to the hell of fire.
Matthew 5:22
============================================
father mike
We don't care to hear your kinky sex solicitations OR what hand you would like them administered with.
============================================ But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, ?You fool!? will be liable to the hell of fire.
Matthew 5:22
============================================
father mike
so it seems to be okay.
Experiment with the transformer core gapping to massage dead time. That is likely one of the elements you need to fix this issue.
We have gapped cores between 0.5 mil and as much as 50 mils for one weird configuration.
Zero gap is bad, and we usually got prime results with between 0.5 mil and 10 mils. Truly, if your transformer is not gapped, it should be, even if only slightly.
And I say to you, asshole, the last time you posted that, you also used one of your rib poke nym morph moves. That makes you guilty of that which you point your little netkkkop jerk wanna be finger at.
You ARE what you bleat.
You are more a troll than I ever could be... and you are pathetic as well. And no, you are not "a father", mike. What you are is SCAT-in-the-hat. That is what is between your ears, and that is what makes up your tears.
The only thing you father are the little dingleberries you spew around the world. You are SCAT-IN-THE-HAT.
Bwuahahahaha!
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