SDGEE #021 2.3" 6 Digit LED Clock Build

[SteveyG]

I recently built a 6 digit LED clock from some 2.3" red 7 segment displays



For anyone interested, I've uploaded the schematics and firmware to my website and uploaded a YouTube video. Enjoy!

http://sdgelectronics.co.uk/ledclock-projects/

[hgg]

Cool project!
Nice work and programming.
I really liked the OLED version.  Any schematics for that?

These 7 segment displays look like they are of very good quality!  The only problem for me is
the multiplexing that produces flickering and can be irritating especially when you look at it
with averted vision.  Its not noticeable by everyone though.

250hz its not bad, but how fast can you make the update rate? 
Alternatively is it possible to add some sort of fade off delay with capacitors for the segments?
This way the flickering will be much less noticeable.  Maybe you can leave a lower delay for the
seconds segment.

If you add a red filter on top of the segments the contrast will increase dramatically.
Nice work!
George.

[SteveyG]

The microcontroller is barely breaking a sweat at 250Hz, so it's likely that the refresh rate could be increased by an order of magnitude without any issues. This would simply be a change to the Timer 2 configuration in the code. The 250Hz was chosen so that it didn't cause odd effects with the camera.

Adding capacitors wouldn't work with the circuitry in it's current configuration. I'd advise changing to latches or shift registers and driving the displays statically if the multiplexing is irritating.

I'll have to re-visit the OLED clock at some point and tidy it up. I'll produce some schematics for that at the same time.

Thanks!

[hgg]

I'd advise changing to latches or shift registers and driving the displays statically if the multiplexing is irritating.

Is it more work to drive them statically?  Almost all of the 7 segment display applications I've seen, have
used multiplexing.

I'll have to re-visit the OLED clock at some point and tidy it up. I'll produce some schematics for that at the same time.

I will wait for that!
Thanks.

[SteveyG]

It does add to the bill of materials, and makes things a bit less compact, but there are some situations where they are not multiplexed. I've seen it a lot in legacy medical applications as it was simpler to detect segment failure back then.

[hgg]

Interesting.
Thanks again.