Thanks for your answer Mark,
your proposal was my plan for an "optimal way out" as well, but I posted here, thinking that there may be knowledge available regarding the presented case. Actually, it currently seems as if "a certain kind of" R-Core transformers show that behavior, not just individual pieces.
Regards,
Winfried
your proposal was my plan for an "optimal way out" as well, but I posted here, thinking that there may be knowledge available regarding the presented case. Actually, it currently seems as if "a certain kind of" R-Core transformers show that behavior, not just individual pieces.
Regards,
Winfried
Regarding the snubber circuit results, I see that a lot of the time the Cx and Cs values come out the same.
If I dont have results for my transformer , would one be better off to apply these 2 cap values and leave the resistor out of it....or does the circuit not work at all without the Rs.?
If I dont have results for my transformer , would one be better off to apply these 2 cap values and leave the resistor out of it....or does the circuit not work at all without the Rs.?
It's your equipment and you can use it any way you like. If it makes wiggles on the oscilloscope screen that please you: then you're happy.
However I myself absolutely insist upon always setting Cseries >= 15 * Cparallel . In the notation of the Quasimodo design note, Cs >= 15 * Cx . The recommended starting point for experimentation is
Here in the Quasimodo thread, I have offered the advice "If you know what you're doing, do whatever you like. If you don't know what you're doing, use Cs=0.15uF and Cx=0.01uF". More than once.
And I took that advice myself. I built a power supply for my First Watt "M2x" class A power amplifier, schematic below. Since I knew what I was doing, I set Cs however I liked. I set Cs to be a factor of 142 greater than Cx. Not a factor of 15 ; a factor of 142.
I strongly recommend choosing Cs >= 15 * Cx unless you know exactly what you're doing.
However I myself absolutely insist upon always setting Cseries >= 15 * Cparallel . In the notation of the Quasimodo design note, Cs >= 15 * Cx . The recommended starting point for experimentation is
- Cs = 0.15 uF
- Cx = 0.01 uF
Here in the Quasimodo thread, I have offered the advice "If you know what you're doing, do whatever you like. If you don't know what you're doing, use Cs=0.15uF and Cx=0.01uF". More than once.
And I took that advice myself. I built a power supply for my First Watt "M2x" class A power amplifier, schematic below. Since I knew what I was doing, I set Cs however I liked. I set Cs to be a factor of 142 greater than Cx. Not a factor of 15 ; a factor of 142.
I strongly recommend choosing Cs >= 15 * Cx unless you know exactly what you're doing.
hello,
which type of capacitor best for Cx and Cs?
MKP X2 for AC line, or common MKP such as WIMA.MKP10 or VishayMKP1837 ??
thanks.
which type of capacitor best for Cx and Cs?
MKP X2 for AC line, or common MKP such as WIMA.MKP10 or VishayMKP1837 ??
thanks.
In the documentation Mark mentions the EPCOS B32529 series, which are general purpose PET dielectric film capacitors.
Mouser PN
871-B32529C3154J289
B32529C3154J289 EPCOS / TDK | Mouser
871-B32529C3103K189
B32529C3103K189 EPCOS / TDK | Mouser
Mouser PN
871-B32529C3154J289
B32529C3154J289 EPCOS / TDK | Mouser
871-B32529C3103K189
B32529C3103K189 EPCOS / TDK | Mouser
Nobody knows with perfect certainty, which capacitors are "best", simply because nobody has tried every possible capacitor and evaluated all of them against each other. In fact nobody even knows whether a "best" exists; perhaps 15 different capacitors would turn out to be equally superior, if anyone ever performs the complete and exhaustive testing.
The good news is: you can try out as many different options as you please, on your own personal Quasimodo test jig. If some of them produce waveform shapes on your oscilloscope that you prefer -- that's wonderful! You've successfully found capacitors that please you most.
Or, perhaps more likely, you might gravitate towards certain types of capacitors for preexisting reasons, even before you begin Quasimodo testing. Maybe these capacitors are wrapped in a beautiful sleeve. Maybe they're hand-made and high priced. Maybe an authoritative person proclaimed that these particular capacitors are extra good, and you trust their pronouncements. Maybe they have the words AUDIO GRADE printed on the capacitor body in large letters.
In any case you can plunk down your-favorite-capacitor into Quasimodo and look at the resulting waveforms on your oscilloscope. If the wave shapes you see are pleasing -- that's wonderful! You've discovered that the capacitors you already loved, work acceptably well in Quasomodo. Success!
I myself prefer certain series of capacitor, because it has a particular engineering specification which I feel is especially beneficial. The capacitor and the reason I prefer it, are discussed on page 7 of the Quasimodo design note.
The good news is: you can try out as many different options as you please, on your own personal Quasimodo test jig. If some of them produce waveform shapes on your oscilloscope that you prefer -- that's wonderful! You've successfully found capacitors that please you most.
Or, perhaps more likely, you might gravitate towards certain types of capacitors for preexisting reasons, even before you begin Quasimodo testing. Maybe these capacitors are wrapped in a beautiful sleeve. Maybe they're hand-made and high priced. Maybe an authoritative person proclaimed that these particular capacitors are extra good, and you trust their pronouncements. Maybe they have the words AUDIO GRADE printed on the capacitor body in large letters.
In any case you can plunk down your-favorite-capacitor into Quasimodo and look at the resulting waveforms on your oscilloscope. If the wave shapes you see are pleasing -- that's wonderful! You've discovered that the capacitors you already loved, work acceptably well in Quasomodo. Success!
I myself prefer certain series of capacitor, because it has a particular engineering specification which I feel is especially beneficial. The capacitor and the reason I prefer it, are discussed on page 7 of the Quasimodo design note.
Hi mark. If I use a switch on the secondary to cut the ac voltage, before the bridge.
Should I put the snubber before or after the switch ?
Should I put the snubber before or after the switch ?
thank's 6L6
hunting for MKT caps..
I’d like to know what it is about the suggested (and throughly tested) suggested parts that you find inferior...😕
Hi Stuart,
By all means, if you are nervous about the Quasimodo PCB layout, don't use it! Hundreds of other diyAudio members have built Quasimodo from these exact same Gerber files ... but perhaps that's just a combination of plain dumb luck, plus reluctance to report an unfavorable result.
The Quasimodo schematic is fully disclosed and the parts placement on my 2013 PCB is fully disclosed, including the "IPAK" footprint for the MOSFET. That will save you some time if you decide to re-layout the board. Perhaps you will choose to instantiate a TO-220 MOSFET footprint (?) rather than IPAK. I encourage you to perform this exercise; you'll have fun, you'll learn a couple of things, and best of all, you'll end up with a layout that does . not . make . you . nervous. How valuable is that? (answer: infinitely valuable!)
Seize the day. Create the best electronic designs and PCBs you possibly can. Don't accept compromises. Follow your heart!
MJ
By all means, if you are nervous about the Quasimodo PCB layout, don't use it! Hundreds of other diyAudio members have built Quasimodo from these exact same Gerber files ... but perhaps that's just a combination of plain dumb luck, plus reluctance to report an unfavorable result.
The Quasimodo schematic is fully disclosed and the parts placement on my 2013 PCB is fully disclosed, including the "IPAK" footprint for the MOSFET. That will save you some time if you decide to re-layout the board. Perhaps you will choose to instantiate a TO-220 MOSFET footprint (?) rather than IPAK. I encourage you to perform this exercise; you'll have fun, you'll learn a couple of things, and best of all, you'll end up with a layout that does . not . make . you . nervous. How valuable is that? (answer: infinitely valuable!)
Seize the day. Create the best electronic designs and PCBs you possibly can. Don't accept compromises. Follow your heart!
MJ