Questions: RF noise, double displays

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7 months 8 minutes ago - 6 months 4 weeks ago #12445 by Ty_Eeberfest
Fanout should not be a problem - the microcontroller outputs can source (and sink) more than enough current for what you have in mind.

Here is more than you ever wanted to know about the controller chip:
ww1.microchip.com/downloads/en/DeviceDoc...ga328P_Datasheet.pdf
Page 258 for the pertinent electrical specs.

EDIT: Provided you live where the mains supply is 120VAC, a 1:1 isolation transformer + bridge rectifier + beefy electrolytic filter capacitor provides a nice 170VDC supply for little effort & expense. I've had such a supply running a bank of 16 B-7971 tubes for the last 14 years with zero problems. Some will cringe at the lack of regulation but the practical reality is that with a properly sized capacitor the fluctuations are too small to be seen on the tubes.

Look into it later when the dust is clearing off the crater.
Last edit: 6 months 4 weeks ago by Ty_Eeberfest.

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6 months 3 weeks ago #12456 by Alan7
Thanks, Ty. I'll have a look at the datasheet.

I am not AEW, though it is ironic that I share the initials AE with him. I also follow him, I wish I shared his considerable knowledge!

73
Alan AG5RJ

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5 months 2 weeks ago #12546 by Dkivett
Alan
I was reading this thread and found it very interesting,
I have a crazy idea (probably unusable) could you, run 2 clocks with just 1 wifi module and parallel all the connectors except power
i know you would still have issues with the DST if it weren't for that would i think you could just rearrange the hour pins Maybe someone who has a much better understanding of this could make something usable of this idea
I hope they can help you make this work it sounds like very cool project

Dave

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5 months 2 weeks ago #12547 by Ty_Eeberfest
Dave,

Interesting idea. I don't see how it can be done without a little bit of programming, but I don't think zero-programming was an absolute requirement.

Instead of paralleling everything, I would build them as 2 independent complete clocks, one with WiFi / NTP module and one without. Then I would tie together ground, SDA and SCL of both clocks - nothing more. One clock would need its code modified to give it a different I2C address than the default so we don't end up with duplicate addresses on the bus. The "master" (unit with WiFi) would get modified to repeat the time to the "slave" over I2C periodically - probably every time it gets updated by the WiFi module. Time zone offset logic could go in either the master or the slave. These would not be particularly difficult program mods since I2C handling is already built into the code.

Just a thought.......

Look into it later when the dust is clearing off the crater.

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5 months 2 weeks ago #12550 by Ian
Yes, you could put them on the same bus, and give one of the clocks a different I2C address. The changes in the WiFi unit would be minimal (send the time update to two slaves instead of one).

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5 months 2 weeks ago #12551 by Ty_Eeberfest
Ian, I like the sound of that. Simpler and cleaner than what I was going for with the clock relaying time.

Look into it later when the dust is clearing off the crater.

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