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Hi all,

yes. Another 7 segment clock. But this one turned out too nice to be thrown away and it finally replaces my old “Tiny Edition” design with something I’m a bit more… uhm… less unhappy about.

Actually I’m not really considering publishing further designs right now, but this one was almost done, so here it is.

This one is quite small and using a rather ugly LED strip layout. It does “waste” 7 LEDs. Should you choose to save them you will have to modify the according arrays inside the sketch. A piece of WS2812B LED strip is required, 37 LEDs in total (4x 7 for the digits, 2x for the dots = 30 in use). Doesn’t look very nice from the inside and requires a massive amount of depth added to the whole thing - but it does the trick.

L7/M is smaller than the old “Tiny Edition” and almost exactly the same size as my Lazy Mini Grid.

Biggest part is the outer case. This one is 151.8mm x 63.5mm x 48mm and rotated by 45° it will require a build volume of 148.72mm x 148.72mm x 48mm, so just like my Lazy Mini Grid this one should be printable on a wide range of printers.

I do not recommend this to beginners. You should know about the Arduino IDE and other things - but judging by the past it’s unlikely the ones who should REALLY pay attention are reading this at all. They’re already in the comments section, asking for this:

The pictures show the clock running ClockSketch v7. I highly recommend reading that Instructable before building any of my designs.

Printed parts:

1x L7M-Case.STL
1x L7M-Case_Clips.STL
1x L7M-LED_Frame.STL
1x L7M-Clips_LR.STL
1x L7M-Elec_Case-All.STL (includes a small cable cover, the button clips and the case lid)
1x L7M-Diffusers-All
I recommend printing the diffusers using clear/natural material and the other parts using black. I’ve used black and natural PLA. The amount of material depends on print settings, but it’s roughly ~100g for the black parts and ~30g - ~50g for the diffusers.

Wall widths are always multiples of 0.50mm, so I recommend using an appropiate extrusion width.

Diffusion seems to work better the more material you put into the diffusers. Try to use multiple angles (like 45, -45, 0, 90) for solid infill and avoid too few top layers which might make the infill pattern visible quite easily.

I recommend printing a single digit set at a time to check for the diffusion effect/tolerances. As the picture might suggest I tried a lot of different designs and print settings…

Other parts/electronics:

WS2812B LEDs, 30 LEDs/m

You will need 37 LEDs for this*. The frame will not fit waterproofed or coated strips, only the regular 10mm wide ones which are rather thin (~1mm). There’s some variants using very thick adhesive tape - those will work but aren’t really a pleasure to put in because of the pressure required.

30 LEDs will be used in the finished clock. 4 are “wasted” to avoid soldering between the rows and another 3 are not used (yet) - the ones above/between/below the dots. If required those can be used by adding breakouts and use them for whatever might come to your mind (am/pm, al1/al2 indicators…)

Note: As long as the FastLED library does support them, other LED chipsets will also work. Refer to the FastLED documentation regarding the differences and changes you have to make in that case.

*Obviously you can use 30 LEDs and solder them together for this but you will have to modify the sketch accordingly.

I recommend using a Arduino Nano (AtMega328P) and a DS3231 RTC module. Details can be found in the ClockSketch v7-Instructable.

2x push buttons, 6mm x 6mm, shaft length 1.5mm - 4mm
1x USB cable
1x USB 5V power supply (sketch is limited to 500mA by default but requirements are also dependent on your choice of hardware. A ESP8266 using WiFi will draw much more power than a Nano…)
At low brightness settings the clock will consume around 80-180mA, resulting in <1.0W power draw. So if you happen to have an old USB charger from some device left with only ~350mA or so, this might be a way to utilize it.

Theoretically the maximum power consumption for the 37 LEDs is around 2.2A/11W - this is likely way too much for such a small case printed from PLA, so be careful when playing around with sketches that do not enforce power limits and/or might adress all LEDs!”

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