episode 44: DMX512, ground reference and LED decoration stuff

CBA Podcast

Hi, and an extremely good 2021 to all of you.

We start off this brand new year talking about some totally unrelated and slightly more related new year's resolutions, a miniscule car fix, and glueing with a 3D printing pen. All in not much more detail than stated here.

Continuing on last episode's VGA generator board, I added a DMX512 interface as suggested by some people - thank you for the idea. I found Q Light Controller Plus (qlcplus) a nice and so far solid piece of software for controlling DMX devices from a laptop + USB/RS485 converter cable.

A potential issue (or at least in my head) when making interlinked devices like these, is potentially different ground-potentials depending on which power outlets you use to power networked your device. (See what I did there?) We talk a bit about how to guesstimate the possible magnitude of this difference.

Just for fun I made an xmas LED star-shaped decoration using an existing DIY LED driver board. Reuse everything, recycle success. Also, made a modular transparant acrylic home LED decoration: shine light into the edge of an engraved piece of acrylic. Of course there was failure, this time in the form of hygroscopic LEDs + laziness + oven = damage.

Finally, I made a small power switch PCB, to be placed in between USB power source and USB device: automatically switch the device off when the environment goes dark.

And remember: if YOU want to make this podcast suck less, please send comments, rants, complaints, threats and/or praise. :-)

Relevant links:

• Generic info on stray garbage and some cleanup initiatives (or Dutch version).
• Q Light Controller Plus : software for controlling DMX512 devices.
• The USB-to-RS485 cable I happen to use: USB-RS485-WE.
• Video of DMX512 VGA generator in action
• Tweet (*sigh*...) of star-shaped LED xmas decoration.
• Another tweet (*groan*...) of engraved acrylic LED decoration.

Pics of things talked about:

DMX512 VGA generator boards.

Engraved acrylic LED decoration PCB in action.

...in its base, open...

...and closed up.

LDR USB power switch board...

...and schematic.