When reality kicks your design in the nuts!

A project log for LED Cubular - LED Desktop Cube

Arduino based; 6 PCBs all with 64 LEDs on the outer face to form a li-po powered cube of 384 LED coolness!

Jack FlynnJack Flynn 06/19/2019 at 08:220 Comments

Design to win

So online competitions there's a game to be played. A lot of the time a pretty mock up or design can do better than a more basic working model. Unfortunately when you try to make that pretty design in the real world the reality of manufacture and cost can really kick it in the nuts! With the LED Cubular the design was about meeting the criteria of lower cost but I also have very specific ascetics that I'm trying to achieve. Now that I'm trying to get the first prototypes made I'm finding the "low cost" aspect needs more focus and stock levels really do matter.

Low Stock - Design Change Required

The part - MMT-104-01-L-DH - is a small 2mm pitch 2 row 8 pin surface mount header that looks great in the design and fits in perfect but the stock level is a big fat "0". Like 0 everywhere, so that sucks. I'm going to have to adjust the design and use a more traditional 2.54mm pitch when then increases the overall footprint of the connector and may have further knock on effects. Damn.

High Cost? Kind of..

Looking at the cost factor for the bill of materials the MAX7219CWG+ is roughly £8 a piece and I need 6 per cube. Ouch. The annoying factor for me is that I looked online when making the decision and found a lot of cheap boards on ebay using the MAX7219 so I wrongly assumed it would be possible to pick it up cheaper. As always, getting into the higher quantities brings the cost down but that doesn't help me right now. I may need an alternative to this one...