On Monday, June 26, 2023 at 4:21:09 PM UTC+1, Anthony William Sloman wrote:> On Tuesday, June 27, 2023 at 12:20:48 AM UTC+10, John Woodgate wrote: > > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. > > > > I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine. > If you want to divide by twenty you need five stages of division. The CD4096 contains only two bistables, so it won't do it > > https://pdf1.alldatasheet.com/datasheet-pdf/view/66451/INTERSIL/CD4096BMS.html > > A 4017 is a divide by ten, so if you use one of the J-K bistables in in the 4096 as a divide by two you've got you divide by 20 and can use the other half to drive your oscillation. > > A 4018 is more flexible. > > A small programable logic device could do it in a single packages, but you have to work out how to program it, which isn't all that difficult. > > I was fond of the Philips cool-runner parts about twenty years ago, and they seemed to get even easier to use when Xilinx took them over, but I never bothered to work out how to program them from my home computer (which looked as it it would be easy enough). > > There's probably a chip which does exactly what you want but I've given up reading the Farnell catalogue thoroughly enough to know what it might be today. > > Lasse is probably right about the 32768 oscillator. It won't be as cheap as the crystal on it own but Farnell has lots > > https://www.farnell.com/datasheets/2581434.pdf > > is one of many, and fairly cheap at about $1 each in small quantities. For test gear. why mess around making something you can buy? > > -- > Bill Sloman, SydneyThanks, Bill, I will investigate,
Dividing a 32768 Hz crystal frequency
Started by ●June 26, 2023
Reply by ●June 26, 20232023-06-26
Reply by ●June 26, 20232023-06-26
On a sunny day (Mon, 26 Jun 2023 07:20:43 -0700 (PDT)) it happened John Woodgate <jmw28563@gmail.com> wrote in <2c04cae6-7c55-49c7-911b-ffa77962b987n@googlegroups.com>:>I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequen= >cy for a component bridge. I could use a 4017 and half a a 4013 (sorry abou= >t these ancient devices, but they are still good for some things), but I wo= >uld have to add something to make the crystal oscillate unless there is a w= >ay to use the other half of the 4013 to make the oscillator. > >I also looked at using just a 4096, which gives me the oscillator, but I ca= >n't see how to make it divide by 20. I know there is a technique that comb= >ines some of the output signals via an EXOR to achieve divisors that are no= >t powers of 2, but I can't find information on which signals to combine.If you are not worrried about precison, a simple transistor will make an xtal oscillator: https://panteltje.nl/panteltje/raspberry_pi_dvb-s_transmitter/Raspberry_Pi_DVB-S_transmitter_circuit_diagram_IMG_3961.JPG Note the BC547B, that one is for 6 MHz and drives a normal 74HC counter.
Reply by ●June 26, 20232023-06-26
On Monday, June 26, 2023 at 7:20:48 AM UTC-7, John Woodgate wrote:> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge.Those clock/watch crystals are good, but only at wrist temperature; 100ppm frequency variance is close enough for a wall clock. The 'component bridge' application, though, needs frequency purity, which a CMOS clock does not have; you'll get 32 kHz square waves, not a pure sinewave. There's ways (''magic sines') to do a sinewave synthesis, but in the end, you'll undoubtedly want to have a trimmed LC filter in addition to a crystal oscillator, and maybe a bit of gain control. Phase-locking an XR2206 to a crystal clock kinda works, too.
Reply by ●June 26, 20232023-06-26
John Woodgate <jmw28563@gmail.com> Wrote in message:r> On Monday, June 26, 2023 at 4:00:50?PM UTC+1, Lasse Langwadt Christensen wrote:> mandag den 26. juni 2023 kl. 16.20.48 UTC+2 skrev John Woodgate: > > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. > > > > I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.> get a 32768 Hz oscillator instead of a crystal, saves alot of headachesI'm not sure what you mean by 'a 32768 Hz oscillator'? Part number? Web site?7490? Div by 2, and 10 Bit, rusty. But I've used 7490 and 4013 to get odd divisors in the past. Cheers -- ----Android NewsGroup Reader---- https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html
Reply by ●June 26, 20232023-06-26
John Woodgate <jmw28563@gmail.com> Wrote in message:r> On Monday, June 26, 2023 at 4:00:50?PM UTC+1, Lasse Langwadt Christensen wrote:> mandag den 26. juni 2023 kl. 16.20.48 UTC+2 skrev John Woodgate: > > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. > > > > I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.> get a 32768 Hz oscillator instead of a crystal, saves alot of headachesI'm not sure what you mean by 'a 32768 Hz oscillator'? Part number? Web site?-- ----Android NewsGroup Reader---- https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html
Reply by ●June 26, 20232023-06-26
On Mon, 26 Jun 2023 08:53:45 -0700 (PDT), John Woodgate <jmw28563@gmail.com> wrote:>On Monday, June 26, 2023 at 4:09:51?PM UTC+1, John Larkin wrote: >> On Mon, 26 Jun 2023 08:00:44 -0700 (PDT), Lasse Langwadt Christensen >> <lang...@fonz.dk> wrote: >> >> >mandag den 26. juni 2023 kl. 16.20.48 UTC+2 skrev John Woodgate: >> >> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. >> >> >> >> I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine. >> > >> >get a 32768 Hz oscillator instead of a crystal, saves alot of headaches >> Yes. Oscillators made from a crystal and a chip and some caps and >> maybe a resistor, tend to not oscillate. And certainly won't be PPMs >> on-frequency, as a purchased oscillator usually is. >> >> Maybe play with the math and use some other oscillator frequency and >> some easy divisor? >I think I'd be very lucky to find a better combination of crystal frequency and division ratio. But if you could suggest a simple way of getting closer to 1591.55 Hz I would be very interested.You can buy a programmed XO and divide by something easy. https://www.digikey.com/en/products/filter/programmable-oscillators/169?s=N4IgTCBcDaIA4CcD2BzBBDAtpgpgEwAIBjBATwGcAXdAGwKXKIEsab1KkEQBdAGhABsUUEzxQQARgCsABhD84lcQGVKCJgDsU8kJVJwc4vIxABfU0A Or, Digikey has a zillion standard XO frequencies starting at 1 Hz. You could take your frequency and keep multiplying by 2 until you hit something interesting. CD4059/HC4059 is a divide-by-N, which could be used after one of those many XO choices. Add a flop if you need a square wave.
Reply by ●June 26, 20232023-06-26
mandag den 26. juni 2023 kl. 17.49.35 UTC+2 skrev John Woodgate:> On Monday, June 26, 2023 at 4:00:50 PM UTC+1, Lasse Langwadt Christensen wrote: > > mandag den 26. juni 2023 kl. 16.20.48 UTC+2 skrev John Woodgate: > > > I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. > > > > > > I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine. > > get a 32768 Hz oscillator instead of a crystal, saves alot of headaches > I'm not sure what you mean by 'a 32768 Hz oscillator'? Part number? Web site?something like these just supply power and you are done, https://dk.farnell.com/en-DK/w/c/crystals-oscillators/oscillators/standard-oscillators?frequency-nom=32.768khz&range=inc-in-stock&sort=P_PRICE all SMD but it is only 4 pins
Reply by ●June 26, 20232023-06-26
On 26/06/2023 15:20, John Woodgate wrote:> I want to divide a 32768 Hz crystal frequency by 20 to get a stable frequency for a component bridge. I could use a 4017 and half a a 4013 (sorry about these ancient devices, but they are still good for some things), but I would have to add something to make the crystal oscillate unless there is a way to use the other half of the 4013 to make the oscillator. > > I also looked at using just a 4096, which gives me the oscillator, but I can't see how to make it divide by 20. I know there is a technique that combines some of the output signals via an EXOR to achieve divisors that are not powers of 2, but I can't find information on which signals to combine.I'd just use a PIC or similar running a simple loop toggling an output pin. The eight pin parts (always?) have Xtal oscillators. Some have Numerically Controlled Oscillators which might be handy instead of the simple loop. eg PIC16(L)F18313/18323 As others have said, watch crystals are good at watch temperatures, not so good otherwise, so a better spec higher frequency may be the way to go. Or if you want even more betterer, a GPSDO will give a stable 10MHz if the antenna can see satellites. -- Cheers Clive
Reply by ●June 26, 20232023-06-26
John Woodgate <jmw28563@gmail.com> wrote:> I want to divide a 32768 Hz crystal frequency by 20 to get a stable > frequency for a component bridge. I could use a 4017 and half a a 4013 > (sorry about these ancient devices, but they are still good for some > things), but I would have to add something to make the crystal oscillate > unless there is a way to use the other half of the 4013 to make the oscillator. > > I also looked at using just a 4096, which gives me the oscillator, but I > can't see how to make it divide by 20. I know there is a technique that > combines some of the output signals via an EXOR to achieve divisors that > are not powers of 2, but I can't find information on which signals to combine. >Hey, John, Nice to see you back on SED, man! An HC40103 will do it, if you don’t mind a 5% duty cycle. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
Reply by ●June 26, 20232023-06-26
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:> John Woodgate <jmw28563@gmail.com> wrote: >> I want to divide a 32768 Hz crystal frequency by 20 to get a stable >> frequency for a component bridge. I could use a 4017 and half a a 4013 >> (sorry about these ancient devices, but they are still good for some >> things), but I would have to add something to make the crystal oscillate >> unless there is a way to use the other half of the 4013 to make the oscillator. >> >> I also looked at using just a 4096, which gives me the oscillator, but I >> can't see how to make it divide by 20. I know there is a technique that >> combines some of the output signals via an EXOR to achieve divisors that >> are not powers of 2, but I can't find information on which signals to combine. >> > > Hey, John, > > Nice to see you back on SED, man! > An HC40103 will do it, if you don’t mind a 5% duty cycle. >Plus a 74HC1G04 or something for the oscillator. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
