First Sunday in Advent & the PCB Tree (#E16)

Well, looks like it’s the first Sunday in Advent already and I’m too lazy preparing a new post. I’ve been working a bit more than usual lately due to our products likely playing a role in the whole temperature controlled Covid vaccine logistics thing. On the remaining Sundays I’ve been extending my old PCB Christmas tree. It’s been using diffused slow RGB (self) fading LEDs ever since (“100pcs LED Diod 5mm RGB Blink Slow Flash Diffused Light Emitting Diode Rainbow 2Pins Lamp Red Green Blue RGB Flashing 5mm LED”, around 2€ per pack of 100) and quite a few of old PCBs now, some bare and scrapped before assembly, some from tests or failed revisions, and some from defective commercial products like routers, access points, projectors, SAS backplanes, RAM, IoT gateways, hard disks, you name it.

It’s now 48cm tall, weighs 2.6kg and consumes around 8 watts including the 3.3V DC-DC converter losses. Yes, there might be some rogue processor starting up (I like releasing the magic smoke of known guzzlers by applying 30V in reverse), but I’d attribute most of the excess power consumption to the random green gallium phosphide LEDs that are all connected in addition to the color changing LEDs. Those GaP LEDs can be driven excessively hard without the slightest increase in brightness, which makes them only stand out in thermal imaging photos. For entire rows of e.g. switch status LEDs I did apply some low value resistors to limit current, but single LEDs are connected to the overall 3ish volt rail. I had a single PCB that drew 80% or 300mA less after inserting a resistor without the slightest change in brightness. Those GaP dinosaurs really suck in terms of conversion efficacy – but apparently they’re dirt cheap.

Also, Amazon is feeling unable to ship cans of artificial snow to one of the pickup stations. I’d very much like to cover this in a bit of fake snow instead of the threads of hot snot. I’m not going to scour all the local DIY shops due to being fed up with Covid restrictions, sorry – none of these present their range of products online, which is a huge oversight.

Anyway, here’s the tree, enjoy!


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