XO controlled 480Hz Oscillator
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From: Chris on 2 Feb 2010 16:11 On Feb 2, 12:43 pm, Bill Sloman <bill.slo...(a)ieee.org> wrote: > On Feb 2, 7:34 pm, Chris <christopher.man...(a)gmail.com> wrote: > > > > > On Feb 2, 9:58 am, Silvar Beitel <silverbee...(a)net1plus.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 > > > > Would a CD4060B + 7.86432 MHz crystal + 1 resistor (maybe 2) + 2 caps > > > running at 12 volts work for you? Output (rail-to-rail square wave) > > > from Q14. > > > > -- > > > Silvar Beitel > > > That sounds pretty easy divide by 2^14. Would that be a custom > > crystal, or a standard freq? > > Farnell doesn't stock it, so it probably isn't a standard frequency, > but getting a custom frequency in that range is no big deal. > > > I will be trying to repair a 480Hz standard tuning fork. It is > > actually a 960Hz fork that had it's divide by 2 flip flop die. It is > > from a 70's vintage piece of equipment. The fork is hermetically > > sealed with solder in a can. I try to get in there tonight, and if > > the dead part is some obsolete IC or something, I will probably > > replace with a crystal and divider to get my 480Hz. A crystal would > > be more quiet and stable I believe. > > Probably. Look at the 74HC401013 from NCXP or TI if you want to use a > standard crystal - it gives you a programmable 8-bit divider in a > single package, and you can cascade them if you want more bits > > http://www.nxp.com/documents/data_sheet/74HC40103.pdf > > You will have to buffer the output to get a 12V swing, or use the > slower HEF401013BEY from ST Microelectronics. > > -- > Bill Sloman, Nijmegen I found a source of dirt cheap CD4060B's. There are no example circuits in the data sheet. Would just use a very generic xtal oscillator? Thanks, Chris KQ6UP
From: Bill Sloman on 2 Feb 2010 19:42 On Feb 2, 10:11 pm, Chris <christopher.man...(a)gmail.com> wrote: > On Feb 2, 12:43 pm, Bill Sloman <bill.slo...(a)ieee.org> wrote: > > > > > > > > > On Feb 2, 7:34 pm, Chris <christopher.man...(a)gmail.com> wrote: > > > > On Feb 2, 9:58 am, Silvar Beitel <silverbee...(a)net1plus.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 > > > > > Would a CD4060B + 7.86432 MHz crystal + 1 resistor (maybe 2) + 2 caps > > > > running at 12 volts work for you? Output (rail-to-rail square wave) > > > > from Q14. > > > > > -- > > > > Silvar Beitel > > > > That sounds pretty easy divide by 2^14. Would that be a custom > > > crystal, or a standard freq? > > > Farnell doesn't stock it, so it probably isn't a standard frequency, > > but getting a custom frequency in that range is no big deal. > > > > I will be trying to repair a 480Hz standard tuning fork. It is > > > actually a 960Hz fork that had it's divide by 2 flip flop die. It is > > > from a 70's vintage piece of equipment. The fork is hermetically > > > sealed with solder in a can. I try to get in there tonight, and if > > > the dead part is some obsolete IC or something, I will probably > > > replace with a crystal and divider to get my 480Hz. A crystal would > > > be more quiet and stable I believe. > > > Probably. Look at the 74HC401013 from NCXP or TI if you want to use a > > standard crystal - it gives you a programmable 8-bit divider in a > > single package, and you can cascade them if you want more bits > > >http://www.nxp.com/documents/data_sheet/74HC40103.pdf > > > You will have to buffer the output to get a 12V swing, or use the > > slower HEF401013BEY from ST Microelectronics. > > > -- > > Bill Sloman, Nijmegen > > I found a source of dirt cheap CD4060B's. There are no example > circuits in the data sheet. Would just use a very generic xtal > oscillator? The original RCA data sheet referrred you to ICAN-6539 which I can't find. Natonal Semiconductor wrote a similar application note http://www.fairchildsemi.com/an/AN/AN-340.pdf which might be useful. -- Bill Sloman, Nijmegen
From: Uwe Hercksen on 3 Feb 2010 06:09 Tim Wescott schrieb: > Dunno if one would go down to 480Hz, but if it did it'd be the way to go. Hello, but if they deliver only a multiple of 480 Hz less external frequency dividers would be necessary compared with a crystal oscillator only. Bye
From: Uwe Hercksen on 3 Feb 2010 06:19 Vladimir Vassilevsky schrieb: > 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. Hello, but for 480 Hz out of 12 MHz, the divider is 25. If a square wave is necessary, better use a 24 MHz crystal and divide two times by five and then by two. Bye
From: Spehro Pefhany on 3 Feb 2010 07:49
On Tue, 2 Feb 2010 08:29:47 -0800 (PST), the renowned Chris <christopher.maness(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 I'd suggest a PIC12F508 and a standard 3.6864MHz crystal (eg. Citizen HC49US-3.6864MABJ-UB) which total less than $2 one-off. To get exact 50% duty cycle 480Hz square waves you need exactly 960 instruction cycles between toggles during which time you can count down from 255 a few times, count down from something less than 255 once, and yank the leash of the WDT, and loop back. Easily done in a handful of lines of assembler. No need for interrupts, timers or any other fancy stuff. If start-up really has to be guaranteed, best to use an external reset chip (eg. MCP100) or use a chip with built-in BOR. It would be possible to use something like a 12F635 (which is guaranteed to work to 20MHz) and a 12.000MHz crystal, setting up all the additional registers (to turn off the analog stuff etc.) would be somewhat irritating and tedious for a one-off job. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff(a)interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |