Fully Discrete Switched PS - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th May 2005, 02:15 PM   #11
Bakmeel is offline Bakmeel  Netherlands
diyAudio Member
 
Bakmeel's Avatar
 
Join Date: Jan 2002
Location: The Netherlands
Default Solid State DC-DC conversion

Well, if you plan on using a transformer for mains isolation, I think the safety subject is already solved.

But for control issues, I believe it is best to work on a buck topology rather than a boost converter. My experience is that if you apply conductance control, buck is best to regulate. You will have to overcome some design limitations such as (dis)continuous mode operation.

My biggest experience so far was a fully discrete boost-topology regulator for an interface with Solar Arrays. A 400W 100V output was realised with a single opamp, two comparators and a few transistors.

So buck/boost self-oscillating discrete DC-DC PSU? very feasible...

Bouke
__________________
More Power Igor! More Power!
  Reply With Quote
Old 26th July 2005, 06:18 AM   #12
rth is offline rth  United States
diyAudio Member
 
rth's Avatar
 
Join Date: Dec 2004
Location: ElevenFootTVland, Ark.
Quote:
How can you use an audio equipment without mains isolation? If you touch the audio input/output terminals, you will die.
That seems like somewhat of an exaggeration! Wouldn't this be ok if it was operated with a GFCI cable or outlet? I'm considering my first power amp project to be a high power (~1.5kw) Class D subwoofer amp that could shake my whole home theater like the woofers do at the cinema. The cheapest/lightest way to do it would be to rectify the mains directly to 170 Vdc then use an H-bridge mosfet switching configuration like you'd see with a hip4080. This is way beyond that chip's voltage rating so either discrete components would have to be used or a pair of half-bridge drivers with something driving them. I really like this idea because it should be very efficient due to the relatively low output current required to make this power at such a high voltage.

Besides instant death, is there a really good reason not to rectify the mains directly?
__________________
construction is done!
  Reply With Quote
Old 26th July 2005, 06:44 AM   #13
diyAudio Member
 
John Biles's Avatar
 
Join Date: May 2005
Location: Victoria Australia
well done Buttsplice, i work as a projectionist and i found your lamp house and Xenon construction, interesting.
keep up the good work.
  Reply With Quote
Old 26th July 2005, 02:48 PM   #14
mzzj is offline mzzj  Finland
diyAudio Member
 
Join Date: Jul 2005
Location: 65N 25E
Quote:
Originally posted by rth


That seems like somewhat of an exaggeration! Wouldn't this be ok if it was operated with a GFCI cable or outlet? I'm considering my first power amp project to be a high power (~1.5kw) Class D subwoofer amp that could shake my whole home theater like the woofers do at the cinema. The cheapest/lightest way to do it would be to rectify the mains directly to 170 Vdc then use an H-bridge mosfet switching configuration like you'd see with a hip4080. This is way beyond that chip's voltage rating so either discrete components would have to be used or a pair of half-bridge drivers with something driving them. I really like this idea because it should be very efficient due to the relatively low output current required to make this power at such a high voltage.

Besides instant death, is there a really good reason not to rectify the mains directly?
I am around same ballpark, exept planning to run it from rectified 230V mains. Lundahl seemed to have 4kV ac rms isolation specified input transformers wich is requirement in here, but maybe i wound my own prototype since in subwoofer application its far more easier than full-range input transformers. I have fluke insulation resistance tester availlable at work(5kv dc), but usually i use variac and oil burner ignition transformer at home, up to 10kV ac rms and measure leakage current with ordinary multimeter standing on top of plastic box. Speaker terminals are big NO-NO at these voltages, and actually normal loudspeakers are also big NO-NO. not any speaker manufacturer can quarantee that their cone is not going to flash trough at 4kV, so i had to build that amplifier directly inside sub box, ground element chassis and fix fine-mesh grounded metal net directly in front of entire speaker element. And i am probably still breaking at least 10 different safety regulations. GFCI is definetely good idea, but even that is useless if useless user is putting his fingers directly to both of output terminals at max volume.

Running it with isolation transformer makes things somewhat easier and thats my option 2, since i have few pieces of 3000VA 230V/230V toroids hanging around.
  Reply With Quote
Old 27th July 2005, 06:30 AM   #15
rth is offline rth  United States
diyAudio Member
 
rth's Avatar
 
Join Date: Dec 2004
Location: ElevenFootTVland, Ark.
What exactly is using 4kV?

60hz transformers are big, heavy, waste power, and cost money I'll probably sample the power devices and I have all the small parts so I think the only thing I'll have to actually pay for is the heatsinks

Even if I decide that isolation is required, I'd prefer to do a switchmode config that chops up the rectified mains then runs through a small high freq transformer... way smaller, very light, and they are cheap to wind
__________________
construction is done!
  Reply With Quote
Old 27th July 2005, 06:48 AM   #16
mzzj is offline mzzj  Finland
diyAudio Member
 
Join Date: Jul 2005
Location: 65N 25E
Quote:
Originally posted by rth
What exactly is using 4kV?

60hz transformers are big, heavy, waste power, and cost money I'll probably sample the power devices and I have all the small parts so I think the only thing I'll have to actually pay for is the heatsinks

Even if I decide that isolation is required, I'd prefer to do a switchmode config that chops up the rectified mains then runs through a small high freq transformer... way smaller, very light, and they are cheap to wind
In here safety regulations call for 4kV dielectric strength between ground and L or N conductor. Means that it has to be able to withstand 4kV rms AC for 1 min without arcing or starting to leak. Bit less in some cases if i remember correctly but i usually built everything to withstand 4kV so i dont need remember every exeption of regulations. And 6mm creepage distance is required for uninsulated parts. This can be a real bugger in SMPS transformers when half of core widht is lost to creepage distances.

In US somewhat less than 4kV is sufficient but its not my business what UL or whatever says there.
  Reply With Quote
Old 27th July 2005, 12:29 PM   #17
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
You can easily build a high quality linear regulator which will do more than 4 amps -- use the LM317HV and wrap an NPN power transistor around it. National Semi will tell you how in the application notes for the LM317HV -- although they show use of their super-matched pair transistors. Using the LM317HV will definately be quieter and easier to build than an SMPS.

You can also scale the Pooge 5.5.1 for higher current, higher voltage...
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Switched DC/DCconverter for B+ revintage Tubes / Valves 18 23rd July 2007 07:18 PM
Discrete fully differential amps and no CMFB rtarbell Solid State 1 24th August 2006 06:22 AM
My fully discrete ClassD MikeB Class D 138 26th November 2005 10:32 PM
Switched mode PSU - parts? miguel2 Parts 1 26th September 2003 03:48 PM
Switched capacitor filters Petervg Solid State 21 18th August 2002 09:45 PM


New To Site? Need Help?

All times are GMT. The time now is 02:06 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2