On 19/07/2015 18:26, Bill Sloman wrote:> On Sunday, July 19, 2015 at 1:49:42 AM UTC+2, M Philbrook wrote: >> In article <c228b7df-ec64-469a-ae5f-f4ae29cfe028@googlegroups.com>, >> bill.sloman@gmail.com says... >>> >>> On Saturday, July 18, 2015 at 5:50:11 PM UTC+2, John Larkin wrote: >>>> On Sat, 18 Jul 2015 09:39:34 -0400, bitrex >>>> <bitrex@de.lete.earthlink.net> wrote: >>>> >>>>> >>>>> For a hobby project, I'd like to be able to generate +48 volts or so >>>> >from +5 volt USB. Current requirements are small, maybe 15 mA or so? >>>>> I'd like uh, low noise (I don't have an exact spec so this is just kind >>>>> of existential at this point), so maybe a charge pump would be in order >>>>> rather than a boost switcher? >>>>> >>>>> Does anyone make a charge pump IC that I could feed an external clock >>>>> to, with outputs suitable for running something like a Dickson pump? >>>>> Maybe that would be too many stages to go from +5 to +48... >>>> >>>> Two of these >>>> >>>> http://www.digikey.com/product-detail/en/PDS1-S5-S24-M-TR/102-2973-2-ND/4006941 >>>> >>>> with the outputs in series would work. They are fairly quiet, and you >>>> could add a little filtering to help. At light loads, their output >>>> tends to be a few per cent high. But then, 5 volts from USB may not >>>> really be 5 volts. >>>> >>>> For really quiet, consider some sort of sinewave drive step-up >>>> transformer. >>> >>> A Baxandall Class-D oscillator - one step-up transformer and one inductor - would work well. MOS-FET transistors do a bit better than bipolar transistors, but Baxandall's paper rather pre-dates them. >>> >>> http://sophia-elektronica.com/0344_001_Baxandal.pdf >>> >>> http://sophia-elektronica.com/Baxandall_parallel-resonant_Class-D_oscillator1.htm >> >> Oh God, You just couldn't keep that failed OSC out of the subject! > > The 1959 Baxandall class_D oscillator isn't "failed". To quote from my web-site "The circuit is probably best known from Jim Williams' series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65)." These apparently were Linear Technology's most popular application notes for quite a while. > > It has been claimed that Jim Williams got the circuit from England, without the Baxandall label. > > I do have a low distortion variant of the class-D oscillator, with a current mirror rather than the feed inductor, but that's not the low distortion oscillator I'm working on at the moment. > > You are distinctly public-spirited in regularly reminding us that you are an idiot, but you really don't have to do it quite as often as you do. >The circuit on your website bears a lot of resemblance to the one in Figure 2 of G3VA's Technical Topics column in Radio Communications magazine from May 2002. He refers to it as the "Mesny VHF power oscillator of the 1920s" though of course then it used triodes not MOSFETs, and needed a separate winding for the gates to get the DC bias right. There is a picture of it under the name Mesny here: http://www.r-type.org/articles/art-106.htm I think some people call them Kalitrons too: http://www.vk6fh.com/vk6fh/kalitron.htm It is one of the most popular topologies for on-chip LC oscillators in the synthesisers of cellphone radios - though usually with fancy amplitude control etc. and sometimes without the inductor in the supply, or with the supply inductor moved to the tail of the diff pair. Whatever it is called, it was a very old topology in 1959 and yet billions of them have been made in recent years. Chris
charge pump/boost converter
Started by ●July 18, 2015
Reply by ●July 19, 20152015-07-19
Reply by ●July 19, 20152015-07-19
In article <8ea10652-9957-4b3f-8076-c96625387925@googlegroups.com>, bill.sloman@gmail.com says...> > Oh God, You just couldn't keep that failed OSC out of the subject! > > The 1959 Baxandall class_D oscillator isn't "failed". To quote from my web-site "The circuit is probably best known from Jim Williams' series of application notes for Linear Technology, on high frequency inverters for driving cold cathode back-lights used in laptop computers (application notes AN45, AN49, AN51, AN55, AN61, AN65)." These apparently were Linear Technology's most popular application notes for quite a while. > > It has been claimed that Jim Williams got the circuit from England, without the Baxandall label. > > I do have a low distortion variant of the class-D oscillator, with a current mirror rather than the feed inductor, but that's not the low distortion oscillator I'm working on at the moment. > > You are distinctly public-spirited in regularly reminding us that you are an idiot, but you really don't have to do it quite as often as you do. > > -- > Bill Sloman, Sydney > > > >You know as well I do what was meant by that comment.. Jamie
Reply by ●July 19, 20152015-07-19
On Saturday, July 18, 2015 at 11:33:21 AM UTC-7, Tom Miller wrote:> "bitrex" <bitrex@de.lete.earthlink.net> wrote in message > news:55aa97af$0$11862$4c5ecfc7@frugalusenet.com... > > On 7/18/2015 10:51 AM, Phil Hobbs wrote: > >> On 07/18/2015 10:25 AM, John S wrote: > >>> On 7/18/2015 8:39 AM, bitrex wrote: > >>>> > >>>> For a hobby project, I'd like to be able to generate +48 volts or so > >>>> from +5 volt USB. Current requirements are small, maybe 15 mA or so? > >>>> I'd like uh, low noise (I don't have an exact spec so this is just kind > >>>> of existential at this point), so maybe a charge pump would be in order > >>>> rather than a boost switcher? > >>>> > >>>> Does anyone make a charge pump IC that I could feed an external clock > >>>> to, with outputs suitable for running something like a Dickson pump? > >>>> Maybe that would be too many stages to go from +5 to +48... > >>> > >>> My guess is that it would take 11 stages, possibly more. > >> > >> You can get modules that do most of that for a buck and a half on eBay. > >> http://tinyurl.com/q2qkn2u will do 5->24V, and then a homemade > >> single-stage charge pump will get you 48V. > >> > >> Cheers > >> > >> Phil Hobbs > >> > > > > Oh wow, those are great. They're cheap enough that I could just slap them > > into a "finished" product... > > > > They do not have an isolated output. So connecting them in series to make 48 > volts will not work.The converters John suggested are isolated, you can stack them in series. Phil only suggested using one non-isolated, then a charge pump. So, they are not suggesting to stack the non-isolated converters.
Reply by ●July 19, 20152015-07-19
On Sat, 18 Jul 2015 19:53:31 -0400, M Philbrook <jamie_ka1lpa@charter.net> wrote:>In article <c228b7df-ec64-469a-ae5f-f4ae29cfe028@googlegroups.com>, >bill.sloman@gmail.com says... >> >> On Saturday, July 18, 2015 at 5:50:11 PM UTC+2, John Larkin wrote: >> > On Sat, 18 Jul 2015 09:39:34 -0400, bitrex >> > <bitrex@de.lete.earthlink.net> wrote: >> > >> > > >> > >For a hobby project, I'd like to be able to generate +48 volts or so >> > >from +5 volt USB. Current requirements are small, maybe 15 mA or so? >> > >I'd like uh, low noise (I don't have an exact spec so this is just kind >> > >of existential at this point), so maybe a charge pump would be in order >> > >rather than a boost switcher? >> > > >> > >Does anyone make a charge pump IC that I could feed an external clock >> > >to, with outputs suitable for running something like a Dickson pump? >> > >Maybe that would be too many stages to go from +5 to +48... >> > >> > Two of these >> > >> > http://www.digikey.com/product-detail/en/PDS1-S5-S24-M-TR/102-2973-2-ND/4006941 >> > >> > with the outputs in series would work. They are fairly quiet, and you >> > could add a little filtering to help. At light loads, their output >> > tends to be a few per cent high. But then, 5 volts from USB may not >> > really be 5 volts. >> > >> > For really quiet, consider some sort of sinewave drive step-up >> > transformer. >> >> A Baxandall Class-D oscillator - one step-up transformer and one inductor - would work well. MOS-FET transistors do a bit better than bipolar transistors, but Baxandall's paper rather pre-dates them. >> >> http://sophia-elektronica.com/0344_001_Baxandal.pdf >> >> http://sophia-elektronica.com/Baxandall_parallel-resonant_Class-D_oscillator1.htm > >Oh God, You just couldn't keep that failed OSC out of th subject! > >JamieIt's an interesting circuit from a time scaling standpoint. It will oscillate at tens of KHz, but it takes decades to build. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●July 19, 20152015-07-19
On Sun, 19 Jul 2015 09:54:42 -0700 (PDT), edward.ming.lee@gmail.com wrote:>On Saturday, July 18, 2015 at 11:33:21 AM UTC-7, Tom Miller wrote: >> "bitrex" <bitrex@de.lete.earthlink.net> wrote in message >> news:55aa97af$0$11862$4c5ecfc7@frugalusenet.com... >> > On 7/18/2015 10:51 AM, Phil Hobbs wrote: >> >> On 07/18/2015 10:25 AM, John S wrote: >> >>> On 7/18/2015 8:39 AM, bitrex wrote: >> >>>> >> >>>> For a hobby project, I'd like to be able to generate +48 volts or so >> >>>> from +5 volt USB. Current requirements are small, maybe 15 mA or so? >> >>>> I'd like uh, low noise (I don't have an exact spec so this is just kind >> >>>> of existential at this point), so maybe a charge pump would be in order >> >>>> rather than a boost switcher? >> >>>> >> >>>> Does anyone make a charge pump IC that I could feed an external clock >> >>>> to, with outputs suitable for running something like a Dickson pump? >> >>>> Maybe that would be too many stages to go from +5 to +48... >> >>> >> >>> My guess is that it would take 11 stages, possibly more. >> >> >> >> You can get modules that do most of that for a buck and a half on eBay. >> >> http://tinyurl.com/q2qkn2u will do 5->24V, and then a homemade >> >> single-stage charge pump will get you 48V.$1.49 with free shipping from China. That's crazy.>> >> >> >> Cheers >> >> >> >> Phil Hobbs >> >> >> > >> > Oh wow, those are great. They're cheap enough that I could just slap them >> > into a "finished" product... >> > >> >> They do not have an isolated output. So connecting them in series to make 48 >> volts will not work. > >The converters John suggested are isolated, you can stack them in series.And you can stack them on top of the +5 supply, to get another 5 volts for free. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●July 19, 20152015-07-19
A $1.50 boost and a $1.50 buck connected as an inverter gives the effect of stacking two of the fancier ones, using the isolation of the USB brick. Of course it may not work if the OP needs to use the 5V in the same circuit. Cheers Phil Hobbs
Reply by ●July 19, 20152015-07-19
On 7/19/2015 2:04 PM, Phil Hobbs wrote:> A $1.50 boost and a $1.50 buck connected as an inverter gives the effect of stacking two of the fancier ones, using the isolation of the USB brick. Of course it may not work if the OP needs to use the 5V in the same circuit. > > Cheers > > Phil Hobbs >I am going to need +5/-5 and +48 unfortunately...
Reply by ●July 19, 20152015-07-19
On Sunday, July 19, 2015 at 2:26:18 PM UTC-7, bitrex wrote:> On 7/19/2015 2:04 PM, Phil Hobbs wrote: > > A $1.50 boost and a $1.50 buck connected as an inverter gives the effect of stacking two of the fancier ones, using the isolation of the USB brick. Of course it may not work if the OP needs to use the 5V in the same circuit. > > > > Cheers > > > > Phil Hobbs > > > > I am going to need +5/-5 and +48 unfortunately...Perhaps one cheap non-isolated and one expensive stack-up isolated. A bit expensive, but still much cheaper than what you can build with discretes.
Reply by ●July 19, 20152015-07-19
On 7/19/2015 5:39 PM, edward.ming.lee@gmail.com wrote:> On Sunday, July 19, 2015 at 2:26:18 PM UTC-7, bitrex wrote: >> On 7/19/2015 2:04 PM, Phil Hobbs wrote: >>> A $1.50 boost and a $1.50 buck connected as an inverter gives the effect of stacking two of the fancier ones, using the isolation of the USB brick. Of course it may not work if the OP needs to use the 5V in the same circuit. >>> >>> Cheers >>> >>> Phil Hobbs >>> >> >> I am going to need +5/-5 and +48 unfortunately... > > Perhaps one cheap non-isolated and one expensive stack-up isolated. A bit expensive, but still much cheaper than what you can build with discretes. >If I turn this hobby product into an actual product, space is also at a premium. The current requirements of the -5 volt rail are modest - a while back someone pointed out a circuit that used a MAX232 to generate a negative rail for an entire board. How would the "stack-up isolated" work?
Reply by ●July 19, 20152015-07-19
On Sunday, July 19, 2015 at 2:44:24 PM UTC-7, bitrex wrote:> On 7/19/2015 5:39 PM, edward.ming.lee@gmail.com wrote: > > On Sunday, July 19, 2015 at 2:26:18 PM UTC-7, bitrex wrote: > >> On 7/19/2015 2:04 PM, Phil Hobbs wrote: > >>> A $1.50 boost and a $1.50 buck connected as an inverter gives the effect of stacking two of the fancier ones, using the isolation of the USB brick. Of course it may not work if the OP needs to use the 5V in the same circuit. > >>> > >>> Cheers > >>> > >>> Phil Hobbs > >>> > >> > >> I am going to need +5/-5 and +48 unfortunately... > > > > Perhaps one cheap non-isolated and one expensive stack-up isolated. A bit expensive, but still much cheaper than what you can build with discretes. > > > > If I turn this hobby product into an actual product, space is also at a > premium. The current requirements of the -5 volt rail are modest - a > while back someone pointed out a circuit that used a MAX232 to generate > a negative rail for an entire board. How would the "stack-up isolated" > work?Yes, have John ('s suggestion) sitting on top of Phip ('s suggestion). John would be totally isolated from the rest (Sorry, John, it's just a joke). A Max232 can also generate the negative rail (probably -7 to -10) then regulate it to -5V.
