XO controlled 480Hz Oscillator
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From: Bill Sloman on 5 Feb 2010 08:24 On Feb 5, 4:30 am, George Herold <ggher...(a)gmail.com> wrote: > On Feb 4, 5:14 pm,Bill Sloman<bill.slo...(a)ieee.org> wrote: > > > > > On Feb 4, 4:43 am, George Herold <ggher...(a)gmail.com> wrote: > > > > On Feb 3, 10:05 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- > > > > Web-Site.com> wrote: > > > > On Wed, 3 Feb 2010 06:15:37 -0800 (PST), George Herold > > > > > <ggher...(a)gmail.com> wrote: > > > > >On Feb 2, 11:29 am, Chris <christopher.man...(a)gmail.com> wrote: > > > > >> What is the simplest way to get 480Hz from a crystal controlled > > > > >> oscillator? Looks like most of the pre-packaged XO's and VCXO, seem > > > > >> to put out much higher frequencies. Would a series of dividers be the > > > > >> best way? > > > > > >> Thanks, > > > > >> Chris KQ6UP > > > > > >OK this is probably a stupid idea. But could you phase lock to the > > > > >8th harmonic of the 60Hz line frequency? > > > > > >George H. > > > > > AC Line is sort of sinusoidal, so 8th harmonic content is probably not > > > > all that wonderful, but a PLL with a DIV8 as feedback should work > > > > great... do it all in cheapy CMOS, at low power ;-) > > > > > ...Jim Thompson > > > > -- > > > > | James E.Thompson, CTO | mens | > > > > | Analog Innovations, Inc. | et | > > > > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > > > > | Phoenix, Arizona 85048 Skype: Contacts Only | | > > > > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > > > > | E-mail Icon athttp://www.analog-innovations.com| 1962 | > > > > > I love to cook with wine. Sometimes I even put it in the food. > > > > Yeah, that's what I meant. I've never done a PLL circuit.... But if I > > > can 'restrict' the VCO so that it only 'goes' near 480 Hz, then it > > > should be a simple matter to 'lock-in'. > > > Unfortunately, while the mains frequency it held at precisely 50Hz (or > > 60Hz) over the long term, it can vary by a few percent in the short > > term, so it wouldn't be a good idea for Chris to lock his 480Hz to the > > mains. > > > -- > >Bill Sloman, Nijmegen- Hide quoted text - > > > - Show quoted text - > > Hmm I've never looked that closely at line frequency. Do you have any > idea how long you'd have to average for to 'clean things up'? A few > second time constant is not too bad for an oscillator. I don't really know. As I understand it, if the load on the network gets heavier, the first effect is to slow down the generators and drop the frequency, and the control loop then turns up the power in the steam generator or the gas turbine driving the generator to restore the frequency and push it back above 50Hz (60Hz) for a bit so that all the mains-driven synchronous clocks go back to reading the right time. This is all fairly heay machinery, so a few seconds probably isn't long enough. -- Bill Sloman, Nijmegen
From: JosephKK on 5 Feb 2010 09:23 On Thu, 4 Feb 2010 06:52:50 -0800 (PST), MooseFET <kensmith(a)rahul.net> wrote: >On Feb 3, 9:54 pm, "JosephKK"<quiettechb...(a)yahoo.com> wrote: >> On Tue, 02 Feb 2010 11:56:24 -0600, Tim Wescott <t...(a)seemywebsite.com> wrote: >> >On Tue, 02 Feb 2010 09:47:50 -0800, Chris wrote: >> >> >>> The simplest way is MCU with external crystal. For 480 Hz output, the >> >>> crystal is likely to be a multiple of 3 MHz. The 12.0 MHz would be the >> >>> most common. >> >> >> Is an MCU the same as a PIC? >> >> >All PICs are MCUs. Not all MCUs are PICs. The top contenders that I >> >know of are the PIC and the AVR from Atmel. There are probably low pin- >> >count 8051 derivatives out there, not to mention the '430 from TI. >> >> >Intersil ought to revive the 1802 core, in a 16-pin package surrounded by >> >all the usual peripherals. >> >> I would certainly like to see them again, i liked the architecture, though many did not. > >If you liked the 1802, I assume you also like wacking your thumb with >a hammer. If you want a grotesque architecture try the Fairchild 3850 uP. I guarantee the 1802 is sweetness and light by comparison. And my thumbs are all perfectly safe from my several hammers.
From: MooseFET on 5 Feb 2010 09:23 On Feb 5, 5:24 am, Bill Sloman <bill.slo...(a)ieee.org> wrote: > On Feb 5, 4:30 am, George Herold <ggher...(a)gmail.com> wrote: > > > > > On Feb 4, 5:14 pm,Bill Sloman<bill.slo...(a)ieee.org> wrote: > > > > On Feb 4, 4:43 am, George Herold <ggher...(a)gmail.com> wrote: > > > > > On Feb 3, 10:05 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- > > > > > Web-Site.com> wrote: > > > > > On Wed, 3 Feb 2010 06:15:37 -0800 (PST), George Herold > > > > > > <ggher...(a)gmail.com> wrote: > > > > > >On Feb 2, 11:29 am, Chris <christopher.man...(a)gmail.com> wrote: > > > > > >> What is the simplest way to get 480Hz from a crystal controlled > > > > > >> oscillator? Looks like most of the pre-packaged XO's and VCXO, seem > > > > > >> to put out much higher frequencies. Would a series of dividers be the > > > > > >> best way? > > > > > > >> Thanks, > > > > > >> Chris KQ6UP > > > > > > >OK this is probably a stupid idea. But could you phase lock to the > > > > > >8th harmonic of the 60Hz line frequency? > > > > > > >George H. > > > > > > AC Line is sort of sinusoidal, so 8th harmonic content is probably not > > > > > all that wonderful, but a PLL with a DIV8 as feedback should work > > > > > great... do it all in cheapy CMOS, at low power ;-) > > > > > > ...Jim Thompson > > > > > -- > > > > > | James E.Thompson, CTO | mens | > > > > > | Analog Innovations, Inc. | et | > > > > > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > > > > > | Phoenix, Arizona 85048 Skype: Contacts Only | | > > > > > | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | > > > > > | E-mail Icon athttp://www.analog-innovations.com| 1962 | > > > > > > I love to cook with wine. Sometimes I even put it in the food. > > > > > Yeah, that's what I meant. I've never done a PLL circuit.... But if I > > > > can 'restrict' the VCO so that it only 'goes' near 480 Hz, then it > > > > should be a simple matter to 'lock-in'. > > > > Unfortunately, while the mains frequency it held at precisely 50Hz (or > > > 60Hz) over the long term, it can vary by a few percent in the short > > > term, so it wouldn't be a good idea for Chris to lock his 480Hz to the > > > mains. > > > > -- > > >Bill Sloman, Nijmegen- Hide quoted text - > > > > - Show quoted text - > > > Hmm I've never looked that closely at line frequency. Do you have any > > idea how long you'd have to average for to 'clean things up'? A few > > second time constant is not too bad for an oscillator. > > I don't really know. As I understand it, if the load on the network > gets heavier, the first effect is to slow down the generators and drop > the frequency, and the control loop then turns up the power in the > steam generator or the gas turbine driving the generator to restore > the frequency and push it back above 50Hz (60Hz) for a bit so that all > the mains-driven synchronous clocks go back to reading the right time. > > This is all fairly heay machinery, so a few seconds probably isn't > long enough. I have looked closely. Over 24 hours there are exactly the right number of cycles. Over shorter time frames, the number of cycles per unit time gets worse the shorter the time. When a heavy load is suddenly applied, the phase can jump in either direction by something like 10 degrees. It depends on where in the phase the load arrived and the nature of the load. The system very quickly comes back to normal phase and amplitude. If you live near an industrial area, you may even see periodic modulations of the phase of the mains. Things like punch presses draw surges of power for the electric motors.
From: Spehro Pefhany on 5 Feb 2010 09:44 On Thu, 4 Feb 2010 14:14:11 -0800 (PST), Bill Sloman <bill.sloman(a)ieee.org> wrote: >On Feb 4, 4:43�am, George Herold <ggher...(a)gmail.com> wrote: >> On Feb 3, 10:05�am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >> >> >> >> Web-Site.com> wrote: >> > On Wed, 3 Feb 2010 06:15:37 -0800 (PST), George Herold >> >> > <ggher...(a)gmail.com> wrote: >> > >On Feb 2, 11:29�am, Chris <christopher.man...(a)gmail.com> wrote: >> > >> What is the simplest way to get 480Hz from a crystal controlled >> > >> oscillator? �Looks like most of the pre-packaged XO's and VCXO, seem >> > >> to put out much higher frequencies. �Would a series of dividers be the >> > >> best way? >> >> > >> Thanks, >> > >> Chris KQ6UP >> >> > >OK this is probably a stupid idea. �But could you phase lock to the >> > >8th harmonic of the 60Hz line frequency? >> >> > >George H. >> >> > AC Line is sort of sinusoidal, so 8th harmonic content is probably not >> > all that wonderful, but a PLL with a DIV8 as feedback should work >> > great... do it all in cheapy CMOS, at low power ;-) >> >> > � � � � � � � � � � � � � � � � � � � � ...Jim Thompson >> > -- >> > | James E.Thompson, CTO � � � � � � � � � � � � � �| � �mens � � | >> > | Analog Innovations, Inc. � � � � � � � � � � � � | � � et � � �| >> > | Analog/Mixed-Signal ASIC's and Discrete Systems �| � �manus � �| >> > | Phoenix, Arizona �85048 � �Skype: Contacts Only �| � � � � � � | >> > | Voice:(480)460-2350 �Fax: Available upon request | �Brass Rat �| >> > | E-mail Icon athttp://www.analog-innovations.com|� �1962 � � | >> >> > I love to cook with wine. � � Sometimes I even put it in the food. >> >> Yeah, that's what I meant. �I've never done a PLL circuit.... But if I >> can 'restrict' the VCO so that it only 'goes' near 480 Hz, then it >> should be a simple matter to 'lock-in'. > >Unfortunately, while the mains frequency it held at precisely 50Hz (or >60Hz) over the long term, it can vary by a few percent in the short >term, so it wouldn't be a good idea for Chris to lock his 480Hz to the >mains. A few percent seems way high to me for the North American power grid. 0.03Hz = 0.05% will apparently affect power transfer by 1 GW. IIRC, HP wrote a report many years ago in which short term stability was of the order of a tenth or two tenths of a percent.
From: Fred Bartoli on 5 Feb 2010 09:56
Spehro Pefhany a �crit : > On Thu, 4 Feb 2010 14:14:11 -0800 (PST), Bill Sloman > <bill.sloman(a)ieee.org> wrote: > >> On Feb 4, 4:43 am, George Herold <ggher...(a)gmail.com> wrote: >>> On Feb 3, 10:05 am, Jim Thompson <To-Email-Use-The-Envelope-I...(a)My- >>> >>> >>> >>> Web-Site.com> wrote: >>>> On Wed, 3 Feb 2010 06:15:37 -0800 (PST), George Herold >>>> <ggher...(a)gmail.com> wrote: >>>>> On Feb 2, 11:29 am, Chris <christopher.man...(a)gmail.com> wrote: >>>>>> What is the simplest way to get 480Hz from a crystal controlled >>>>>> oscillator? Looks like most of the pre-packaged XO's and VCXO, seem >>>>>> to put out much higher frequencies. Would a series of dividers be the >>>>>> best way? >>>>>> Thanks, >>>>>> Chris KQ6UP >>>>> OK this is probably a stupid idea. But could you phase lock to the >>>>> 8th harmonic of the 60Hz line frequency? >>>>> George H. >>>> AC Line is sort of sinusoidal, so 8th harmonic content is probably not >>>> all that wonderful, but a PLL with a DIV8 as feedback should work >>>> great... do it all in cheapy CMOS, at low power ;-) >>>> ...Jim Thompson >>>> -- >>>> | James E.Thompson, CTO | mens | >>>> | Analog Innovations, Inc. | et | >>>> | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | >>>> | Phoenix, Arizona 85048 Skype: Contacts Only | | >>>> | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | >>>> | E-mail Icon athttp://www.analog-innovations.com| 1962 | >>>> I love to cook with wine. Sometimes I even put it in the food. >>> Yeah, that's what I meant. I've never done a PLL circuit.... But if I >>> can 'restrict' the VCO so that it only 'goes' near 480 Hz, then it >>> should be a simple matter to 'lock-in'. >> Unfortunately, while the mains frequency it held at precisely 50Hz (or >> 60Hz) over the long term, it can vary by a few percent in the short >> term, so it wouldn't be a good idea for Chris to lock his 480Hz to the >> mains. > > A few percent seems way high to me for the North American power grid. > 0.03Hz = 0.05% will apparently affect power transfer by 1 GW. IIRC, HP > wrote a report many years ago in which short term stability was of the > order of a tenth or two tenths of a percent. > Know zilch about that stuff but all the generator are interconnected through the power grid. This means that they all have to be at the exact same frequency or a gigantic firework will start, and only a phase shift can be tolerated between them. Also having a network of long transmission lines with servoed sources here or there and varying loads might be a nightmare to design and get stable. -- Thanks, Fred. |