A chaotic oscillator is an electronic circuit that can exhibit “chaotic“, nonperiodic behavior. A commonly cited example is Chua’s circuit, but there are many others. I always regarded these as carefully designed, rather academic, examples. So I was a bit surprised to observe apparently chaotic behavior in a completely unrelated experiment.
To test my LED Stair Lighting Controller boards I needed a 12V power supply that can deliver a lot of current. For this I chose a SP-320-12 from meanwell. However with the screw terminals it is not easy to use on a lab bench, also there is no display to monitor the output current. Therefore I build an enclosure around the PSU, and added a volt and ampere meter.
Two years ago, the Gigatron arrived on the retrocomputing scene. It needs just 930 logic gates (packed into 33 standard 7400-series ICs) to create a computer that beat ‘complex’ 1980s home computers like the VIC-20 in terms of both CPU power and graphics. Without microprocessor, graphics, or even an ALU chip, the machine can do this sort of thing with effectively only half of the transistor count inside the 6502 CPU alone. Quite a feat, but more importantly, the hardware is simple enough so that anyone can figure out how it works. Read about it in my previous post
Many of the current bulbs on the market are based on the same chip, the ESP8266. These bulbs are very easy to “hack” and replace the firmware in them with the likes of my ActoSenso or the more widely known and used Tasmota. However, not all bulbs use the same chip. One of my bulbs turned out to have a Broadlink BL3336T-P WiFi module in it. This chip is not open source and not well documented (like the ESP8266 family), so anyone trying to write new firmware for it must first figure out what exactly the chip does and how exactly it does it. This is not an impossible task – some have managed to make great progress on figuring out the inner workings of it, but it is a slow, hit and miss process. In this article I will show a different approach: I replaced the WiFi chip along with its PCB and other parts that drive the LEDs and designed a new, drop-in replacement based on the ESP8266 chip.
Now that I have a solar-powered 12V battery, how can I charge my laptop from it? An inverter would seem absurdly inefficient, converting from 12V DC to 110V AC just so I can connect my Apple charger and convert back to DC. It would work, but surely there’s some way to skip the cumbersome inverter and charge a MacBook Pro directly from DC? Newer Macs feature USB Type C power delivery, a common standard with readily available 12V DC chargers designed for automotive use. But my mid-2014 MBP uses Apple’s proprietary MagSafe 2 charging connector. In their infinite wisdom, Apple has never built a 12V DC automotive MagSafe 2 charger – only AC wall chargers. There are some questionable-looking 3rd-party solutions available, but I’d rather build my own.