The DS3232 has an internal crystal, with periodic temperature compensation (every 100 seconds). There are also non-volatile trim registers that allow you to fine-tune the trimming even further, though I have not needed to do that.
You wont be able to use a scope to fine-tune the crystal oscillator, because the scope wont have sufficient precision or accuracy. A frequency counter is a starting point, but in the end you will need to measure the time over a period of days to get it accurate. Many years ago I had a clock-calendar in my S100 computer, and I would tweak the trim capacitor every few days. After a week it was really close. There were no cellphones, GPS receivers, or NTP servers to get the time; you had to call the phone company for a recorded message with the time, or catch a radio/TV station identification. On Tuesday, April 20, 2021 at 9:27:56 AM UTC-7 MrThe50sanchez wrote: > Hello David! > > that's awesome, I really like the idea, I just bought an oscilloscope but > a really cheap one, the only one I could affort. > > I will try make some change's on the watch to catch a Via to connect the > oscilloscope to it and take a good look to the frecuencia to try to get > that 32.768 KHz frecuency. > > I love the idea of the variable capacitor, it is a really really good idea > guys. > > > Thanks a lot for the comments, now I have more ways to keep studiying this > methods and components. > > > Thanks! > > El lunes, 19 de abril de 2021 a las 19:26:41 UTC+2, nixiebunny escribió: > >> My Nixie watches have a variable 5-30pF capacitor on the crystal so that >> I can adjust the oscillator to exactly 32768 Hz. You could use a different >> value depending on your crystal characteristics. I use an old Hewlett >> Packard universal frequency counter, running in time period averaging mode, >> measuring the time period of 10,000 cycles of the oscillator. >> I connect an oscilloscope probe to the oscillator output pin on the PIC >> computer to achieve minimum loading of the crystal circuit. I have to >> adjust it to run a bit slow with the probe connected, to get proper >> timekeeping when the probe is removed. >> I can adjust it to within one second per week using this technique. I've >> done this on 2000 Nixie watches by now, so it works. >> >> >> On Mon, Apr 19, 2021, 1:23 AM MrThe50sanchez <the50s...@gmail.com> wrote: >> >>> Hello Guys! >>> >>> I have a nice question to ask you guys if you can give me some help. >>> >>> I builded a Nixie watch, It works good, but I'm having a little bit of >>> time delay, 1* min within 6 hours. * >>> >>> At the *first time,* I had 6 min delay for 6 hours aproximately. I >>> investigated the relation of the cristal and the capacitors you need to >>> install with it. First, I had 22pF for a cristal that requires 12.5pF, >>> giving me that 6 min delay for 6 hours, then, I realised these and >>> installed 10Pf capacitor and the delay decreased to 1 minute for 6 hours, >>> and I just ordered new capacitors of 12pF to get more closer to the >>> manufacture requires, So I imagine that the delay is gonna get less. >>> >>> ·Is there any way to make this time delay shorter? >>> ·Do you recommend me a tipe of cristal that is really acurate to install >>> on my watch? >>> >>> Thanks a lot nixie lover's >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "neonixie-l" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to neonixie-l+...@googlegroups.com. >>> To view this discussion on the web, visit >>> https://groups.google.com/d/msgid/neonixie-l/7ce2b557-f652-44b2-a71f-ed75b96ea06fn%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/neonixie-l/7ce2b557-f652-44b2-a71f-ed75b96ea06fn%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/021420aa-d7fc-4f1c-bc70-4a9cbbc5ba8bn%40googlegroups.com.
