Re: Tiny universal clock PCB

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7 years 11 months ago #5528 by kay486
Replied by kay486 on topic Re: Tiny universal clock PCB
Oh by the way, are you sure about the 180V ? It seems quite high to me, most tubes work nicely on lower volategs even lower that those in original datasheets, like 160V and less.

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7 years 11 months ago #5529 by Nisei
Replied by Nisei on topic Re: Tiny universal clock PCB

mjsangster wrote: Oops! Labeled the 26 pin connector wrong - should be 'anode set'.

The alarm and AM/PM indicators are on the 8 pin connector. I am revising the web page later today to reflect these changes plus additional info.

Cool, thanks.
Oh, another thing that crossed my mind; won't the 2x3 multiplexing make it a bit awkward when you want to use only hours and minutes (4 digits)? That means the first 3 digits need a different resistor than the fourth one? (Could be I'm totally wrong about this).

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7 years 11 months ago #5530 by mjsangster
If only 4 tubes are used, the 4 will be the same brightness. Also, for 4 tube clocks the software can be reconfigured to multiplex 2x2 (not nessesary - but would be a little brighter).

I find 180v strikes the tubes better, especially when it is dark. A higher value resistor is used to keep the current draw the same. It is a simple matter to change a power supply resistor to a lower voltage, if needed.

- Michael Sangster
Cold War Creations
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7 years 11 months ago #5533 by Nisei
Replied by Nisei on topic Re: Tiny universal clock PCB
I see the LEDs need a separate 5V input to the board which can be easily solved by using an LM2596 module next to the board. Are the colons static or can they be set to blink?

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7 years 11 months ago #5534 by mjsangster
Actually the board supplies the +5v for the LEDs - I need to redraw that schematic so it is a little more clear. You can see pin 8 of the I/O connector is +5v (I used the wrong symbols) - it supplies up to 50 mA or so of +5v current.

The colons are under software control - they blink once a second or indicate options setting modes.

- Michael Sangster
Cold War Creations
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7 years 11 months ago #5535 by Nisei
Replied by Nisei on topic Re: Tiny universal clock PCB
Great, even better! Always nice to have a blinking colon when using only 4 digits.

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