...fortunately I got not zapped by my boost converter.
Last time it happened seven years back and was just related to less critical current paths within my right hand. I had forgotten to discharge the rail cap, ... picked the PCB in innocent mind and suddenly catapulted the entire PCB through our laboratory. ...comment of a colleague: '...hm, inconvinient - I remember..'.
But instantaneous heat concentration of 16J in that IGBT (see this thread somewhere earlier) was impressive enough and is pushing me to the advise: Wear glasses.
Except this IGBT-vaporization there happened not so much.
But I am gaining more and more the impression that a lot of unsufficient skilled people are doing dangerous electronic experiments.
Eva:
Regarding the boost there is not more much to say. All settled in the thread. And I am going to use it as it is.
I am not concerned about you. You are handling such stuff anyway. May be you are more relaxed regarding safety standards than I am.
But I do not see the danger to inspire you in a critical way.
I am looking forward to your comments, regarding my halfbridge converter to get proper isolated and stabilized +/-55V from these 450V.
I am planning not show the component values in such circuits anymore. You can get all details by private e-mail. But still not started. I am concentrating in the moment more on the class D amp itself.
Last time it happened seven years back and was just related to less critical current paths within my right hand. I had forgotten to discharge the rail cap, ... picked the PCB in innocent mind and suddenly catapulted the entire PCB through our laboratory. ...comment of a colleague: '...hm, inconvinient - I remember..'.
But instantaneous heat concentration of 16J in that IGBT (see this thread somewhere earlier) was impressive enough and is pushing me to the advise: Wear glasses.
Except this IGBT-vaporization there happened not so much.
But I am gaining more and more the impression that a lot of unsufficient skilled people are doing dangerous electronic experiments.
Eva:
Regarding the boost there is not more much to say. All settled in the thread. And I am going to use it as it is.
I am not concerned about you. You are handling such stuff anyway. May be you are more relaxed regarding safety standards than I am.
But I do not see the danger to inspire you in a critical way.
I am looking forward to your comments, regarding my halfbridge converter to get proper isolated and stabilized +/-55V from these 450V.
I am planning not show the component values in such circuits anymore. You can get all details by private e-mail. But still not started. I am concentrating in the moment more on the class D amp itself.
Moderators:
With reference to other threads, which have been closed for safety reasons, I would agree if you simply remove my schematics (#1 & #24). This would avoid any unskilled attempts to copy it.
Basically I am not a friend of hiding information about dangerous topics, because hiding information is reducing potential know how and by this also causing danger.
Furtheron such circuits are being published by various semiconductor manufacturers ...and they even sell demo boards....
But of course I can accept, if you don't want to show details of such contents in your DIY forum.
With reference to other threads, which have been closed for safety reasons, I would agree if you simply remove my schematics (#1 & #24). This would avoid any unskilled attempts to copy it.
Basically I am not a friend of hiding information about dangerous topics, because hiding information is reducing potential know how and by this also causing danger.
Furtheron such circuits are being published by various semiconductor manufacturers ...and they even sell demo boards....
But of course I can accept, if you don't want to show details of such contents in your DIY forum.
I just can't agree with these trends towards hiding schematics and explanations and closing threads related to some subjects.
Working with electronic equipment at anything but an end-product user level is completely unsafe. Safety can't just be guaranteed at all for forum members by limiting the scope of discussion.
That's not only a matter of high voltages or mains isolation, everything can potentially hurt an untrained operator during electronics work or experimentation. Some examples:
- Soldering irons can cause severe burns and fire.
- Solder and most components and materials employed contain toxic substances and produce very dangerous fumes when they smoke (not to mention swallowing, children, etc...)
- Capacitors, transistors and vacuum tubes can explode (imagine those small glass fragments being shot and hitting the face of somebody).
- Audio amplifiers can and do catch fire with something goes wrong. There is a potential fire hazzard.
- Mains transformers are *not* perfect, they may fail losing its secondary winding isolation capabilities when not handled properly (overload, scratches to the windings, shocks, improper mounting of toroids etc..)
- Batteries can just explode, or they can leak very corrosive acids and explosive fumes when not handled properly (and even during normal charge!!)
I think that everybody attempting DIY with the help of this forum should be enforced to read some kind of disclaimer and sign some kind of "terms and conditions" electronic certificate freeing the forum from any responsability shall injuries or damage arise.
Then again, we are signing that kind of "if somebody goes wrong it's not our fault" certificates everytime we install a new program and nobody complains.
Working with electronic equipment at anything but an end-product user level is completely unsafe. Safety can't just be guaranteed at all for forum members by limiting the scope of discussion.
That's not only a matter of high voltages or mains isolation, everything can potentially hurt an untrained operator during electronics work or experimentation. Some examples:
- Soldering irons can cause severe burns and fire.
- Solder and most components and materials employed contain toxic substances and produce very dangerous fumes when they smoke (not to mention swallowing, children, etc...)
- Capacitors, transistors and vacuum tubes can explode (imagine those small glass fragments being shot and hitting the face of somebody).
- Audio amplifiers can and do catch fire with something goes wrong. There is a potential fire hazzard.
- Mains transformers are *not* perfect, they may fail losing its secondary winding isolation capabilities when not handled properly (overload, scratches to the windings, shocks, improper mounting of toroids etc..)
- Batteries can just explode, or they can leak very corrosive acids and explosive fumes when not handled properly (and even during normal charge!!)
I think that everybody attempting DIY with the help of this forum should be enforced to read some kind of disclaimer and sign some kind of "terms and conditions" electronic certificate freeing the forum from any responsability shall injuries or damage arise.
Then again, we are signing that kind of "if somebody goes wrong it's not our fault" certificates everytime we install a new program and nobody complains.
Eva, those are some very good thoughts. I have a few too.
Fumes from venting electrolytic capacitors can be very irritating to the respiratory passages. Their general toxicity may also be a factor.
I think the only quite safe power source is probably a wall wart or similar low power/low voltage supply. But they cannot power much of an amplifier and are rather inconvenient with regard to outlet space utilization. Another fairly safe power source is the carbon-zinc battery. However, it provides even less power than most power adapters.
As a career electronics person, I accept some well-known risk. But I realize there are many much less serious folks out there.
Fumes from venting electrolytic capacitors can be very irritating to the respiratory passages. Their general toxicity may also be a factor.
I think the only quite safe power source is probably a wall wart or similar low power/low voltage supply. But they cannot power much of an amplifier and are rather inconvenient with regard to outlet space utilization. Another fairly safe power source is the carbon-zinc battery. However, it provides even less power than most power adapters.
As a career electronics person, I accept some well-known risk. But I realize there are many much less serious folks out there.
Guys, we don't hide anything. Those threads are still out in the open and can be read by anyone. Some topics are by their nature more dangerous than others, and directly powered amps and TV repairs are two that are highly dangerous to the inexperienced, and so, after much deliberation, we decided not to allow them. We want to keep all of you guys alive and contributing, whatever level of experience you have. 
I haven't chimed in this thread until now, because I have had nothing constructive to contribute to it, but have been regularly watching it, because it is interesting to me.
I have to agree that there always will be a cretain element of risk that goes along with our DIY hobby. EVA gave some excellent examples. This is something we all understand.
Electronically signing a waiver-release statement , while a great idea, might not be very practical, due to the varying nature of liability laws in different countries. What I think might be useful is a general disclaimer on the logon webpage, something stating that navigation about, and registering, in the DIYAduio website constitutes acceptance of liability-waiver terms. If the user (or websurfer) does not agree to the terms (what ever they may end up being) then they are automatically navigated away from the DIYAudio website all together. Kinda like being "escorted" out of the bar by the bouncers.
I dunno, this is just my two cents worth. But I will continue to read this (and other) threads, and post where I can be of help, or ask for help. BTW, Chocoholic, I would be interested in seeing your schematic. If you are so inclined to do, please email me (privately) about that- I would be interested.
Cheers all,
Steve
I have to agree that there always will be a cretain element of risk that goes along with our DIY hobby. EVA gave some excellent examples. This is something we all understand.
Electronically signing a waiver-release statement , while a great idea, might not be very practical, due to the varying nature of liability laws in different countries. What I think might be useful is a general disclaimer on the logon webpage, something stating that navigation about, and registering, in the DIYAduio website constitutes acceptance of liability-waiver terms. If the user (or websurfer) does not agree to the terms (what ever they may end up being) then they are automatically navigated away from the DIYAudio website all together. Kinda like being "escorted" out of the bar by the bouncers.
I dunno, this is just my two cents worth. But I will continue to read this (and other) threads, and post where I can be of help, or ask for help. BTW, Chocoholic, I would be interested in seeing your schematic. If you are so inclined to do, please email me (privately) about that- I would be interested.
Cheers all,
Steve
not really off topic but a little off....
I got a PFC module made by astec for cheap and it puts out 380VDC and 950W from 100-240VAC in. should be useful but haven't touched it yet. the voltages are scary.
I'm thinking full bridge? still looking for a trafo core. toroids are out of the question.....
choco, do you already have a supply that will run off that thing? any schematics?
I got a PFC module made by astec for cheap and it puts out 380VDC and 950W from 100-240VAC in. should be useful but haven't touched it yet. the voltages are scary.
I'm thinking full bridge? still looking for a trafo core. toroids are out of the question.....
choco, do you already have a supply that will run off that thing? any schematics?
I might appear irritable to some.. but some of us seasoned power supply designers MUST workout solid state device heating especially when switching IGBT and mosfets are used in the high power range. So many designs are now in the open for all to see. It's not just simply lashing up another device and seeing if it works and might explode. The idea that the switcher may be running cool is one thing....the other is the boost diode my be overheating.
ST has a homepage on boost converters with a download with magnetics sizes.
djQUAN> got a PFC module made by astec for cheap and it puts out 380VDC and 950W from 100-240VAC in. should be useful but haven't touched it yet. the voltages are scary.
I wonder what the efficency is at low line 100V as claimed 950W output ?
Anyone worked it out ?
richj
ST has a homepage on boost converters with a download with magnetics sizes.
djQUAN> got a PFC module made by astec for cheap and it puts out 380VDC and 950W from 100-240VAC in. should be useful but haven't touched it yet. the voltages are scary.
I wonder what the efficency is at low line 100V as claimed 950W output ?
Anyone worked it out ?
richj
richwalters said:
I can easily measure if my PFC is running OK. If all wave shapes are OK. If there are no excessive load conditions. Thermal behaviour as well. But with my normal home equipment I am far away of any chance to figure out the efficacy.
For the input side measurement one can completely forget normal DMM. Scope is not really nice... even if there is a way to come around the reading error of the phase shift. Pick the instantanious power (voltage x current) and integrate it over 10ms....
Still then I have to consider an error of +/-3% in the voltage and -/+4% in the current. The DC output I can measure more accurate. Say 1% in voltage and 1.5% in current.
...if my measurements tells me efficacy=94% this means 94% +/- 9..10% - ah well, we can be sure that we do not exceed 100%...
In the end I am just able to say my efficacy is between 85%...100%,
And sometimes people are trying to convince me that their PFC has 99.97427 % efficacy
djQuan:
Sorry, nothing availabe up to now. But I think a halfbridge will easily do the job. Take care for the isolation in the transformer !!!! And also in voltage measurement with monster isolation optocoupler or well isolated auxiliary winding....
At 400V EN60065 table 11 is demanding for most normal material surface properties (100<CTI<400) creepages between 8mm up to 12.6m. 8mm or 12.6 mm are depending on the applicable degree of dirt. In most home audio applications 8mm should be sufficient.
According table 8 the clearances have to be 4mm. Depending on interpretation of table 9 you would need to add another 0.2mm.
According chapter 14.3.4.1 the min thickness of isolating parts in the bobbin must be at least 0.4mm.
If you discuss isolation of mechanically stressed wires, then even higher thicknesses might be required.... also you have to make sure by mechanics that the creepages/clearances are still guaranted if a copper track gets off the PCB, or a wire soldering might open....
Last but not least it is known that the isolating robustness of most isolators is affected by HF. EN60065 is stating up to 30kHz, but allows application above 30kHz until proper values for higher frequencies will be defined.... But I would expect even more stringend demands within a few years...
And you can be sure that there are many more pifalls in the 158 pages of that safety standard!! Quite inconvinient stuff! Everybody who deals with off line isolation circuits should spend some time with this, or other relevant safety standards.
I have thought about a half bridge setup but thought that it would require more primary windings (not good for cores with not enough space) and that I would need higher voltage fets.
another problem was the supply for the oscillator. I could use a resistor to drop the main 380V rail to the low voltage required by a TL494 but that would give a lot of heat! another option was to power it with an auxiliary winding from the main trafo but how would it run at startup? another was by having an auxiliary linear supply but it also increases size a bit. my best option so far is to power the oscillator with a resistor at startup and disconnect this and power it via an aux winding when the SMPS is running all done automatically by some HV low current transistors....
comments?
another problem was the supply for the oscillator. I could use a resistor to drop the main 380V rail to the low voltage required by a TL494 but that would give a lot of heat! another option was to power it with an auxiliary winding from the main trafo but how would it run at startup? another was by having an auxiliary linear supply but it also increases size a bit. my best option so far is to power the oscillator with a resistor at startup and disconnect this and power it via an aux winding when the SMPS is running all done automatically by some HV low current transistors....
comments?
HV Start-up Circuit
DJ,
Look at this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=69111&highlight=
We discussed, at length, various start-up circuits.look at post #122 and beyond.
Steve
DJ,
Look at this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=69111&highlight=
We discussed, at length, various start-up circuits.look at post #122 and beyond.
Steve
Just as a note, be careful of those HAMers, the FCC will come out and hunt you down with a signal tracker and FINE YOU. So if this PSU actually does emit RF, don't use it very long at a time and be careful...
I may not know what everybody is talking about but this is something I do know...
Just be friendly and you'll be OK...
I may not know what everybody is talking about but this is something I do know...
Just be friendly and you'll be OK...
keantoken said:Just as a note, be careful of those HAMers, the FCC will come out and hunt you down with a signal tracker and FINE YOU. So if this PSU actually does emit RF, don't use it very long at a time and be careful...
I may not know what everybody is talking about but this is something I do know...
Just be friendly and you'll be OK...
You are perfectly right. Especially the gapped choke is some sort of antenna. I am also interested in low radiation and will encapsulate the entire beast. May be I should check it then in our EMI lab... for conductive EMI (probably fine) and radiated EMI... At least I cannot see any influence in my TV, radio or WLAN when running my PFC even without shield.
When you live in China, then you start getting sensible on such things. It is an EMI-hell here. If you want to get your WLAN running you have to spend some efforts in finding a less poluted power plug for the router/acces point ... and search some 'magic points' to position the antennas....
And even then you don't bridge more than one wall + 7m ! Do I have mu-metal walls here?
...in Germany it bridges roughly three times more...
Hi friends,
I'm trying to construct a 1.2kw PFC prototype. I selected IGBT with TO-247 package and I planned to mount IGBT and boost diode on circuit board. But now I have some doubts about mounting them on board because current above 10 amps will pass through them and I think soldering between IGBT and board may be damaged due to high current. What do you think, do you have some practical experince about the subject?
I'm trying to construct a 1.2kw PFC prototype. I selected IGBT with TO-247 package and I planned to mount IGBT and boost diode on circuit board. But now I have some doubts about mounting them on board because current above 10 amps will pass through them and I think soldering between IGBT and board may be damaged due to high current. What do you think, do you have some practical experince about the subject?
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