User:Gsuberland

Hi, I'm Graham! I also go by gsuberland and Polynomial.

Contact

Twitter: @gsuberland

Email: gsuberland at gmail

Interests

• Electronics (particularly if it has a lot of LEDs)
• Security
• Cryptography
• Demoscene
• Stage lighting

Current Projects

Projects that I'm working on right now:

Hackspace Electronics Inventory

Sorting, re-labeling, and cataloguing all of the electronic components we have in the space. See Electronic Components Inventory (2019/2020).

Hot Tub LED installation

I've got an inflatable hot tub with a permanent gazebo (aluminium frame, polycarbonate roof) over it, and I want to run a large number of RGBW lights in there for atmospherics.

The roof's horizontal struts have slots for T-nuts and are effectively just 2020 extrusion. This allows me to bolt lighting channels directly to them. There are four runs at 3m each.

I'm using 720 SK6812 RGBW LEDs in total (3m * 60/m * 4 runs), which comes out at about 58A at 5V, so 290W. It's going to be bright.

Power comes from a 24V/15A supply, which connects to junction boxes on the roof. Each junction box has a point-of-load switching regulator to drop the 24V down to 5V at high current. The power is connected to the LED strips in the channels using MC4 solar panel connectors, and a pair of cables run alongside the LED strips for better current handling.

Data is passed to the strips via Cat5. Each twisted pair contains GND + DATA, and one pair is split off at each junction box to drive a run of LEDs. Preliminary tests show that this should be sufficiently immune to crosstalk and EMI, but if I run into problems with signal integrity the design allows me to easily rig an RS-422 driver and receiver up on each end and make each pair differential.

Control will be done with an ESP32 on a NodeMCU-like board, so I can choose patterns from my phone. The control firmware is a mixed Arduino/FreeRTOS application that runs a web server and drives the LEDs. The code is set up so that each "pattern" is a class that defines the lighting effect, as well as blending modes for automatically fading between patterns.

The power supply and controller will be placed into an outdoor cabinet box that is attached to one of the legs of the gazebo. I will install a cabinet heater to keep the internal temperature above 15C during winter, to avoid condensation. I may also include a piezo buzzer alarm in there for under-temperature and high humidity alarms (via DHT11 sensor).

Current project status: 3 out of 4 junction boxes made. All four LED runs have been assembled. Power supply bought. Most of the code written. Need to source and buy a cabinet.

Home Automation Hub

Inspired by SuperHouse's home automation light switches, I'm designing a switch controller for home automation. Each switch is hooked up via cat5 rather than being connected to the mains.

The main difference between his design and mine is that I have a differential data pair going to each switch panel, allowing for arbitrary serial data to be exchanged with each panel over RS-485. Initially this will be configured more like a single-ended RS-422 bus and will only be used to drive RGB light rings around each panel button, but eventually I plan to include a small MCU on each switch so that I can pass back humidity, temperature, and light level information.

Current project status: In the circuit design phase.

Contact

• Twitter: @gsuberland
• Web: poly.nomial.co.uk