Solid-State Relay
Datasheet Just notes to ensure I know it can be triggered simply with 5V and doesn’t need any external circuitry to make it work.
ESP8266 : GPIO2 challenges
How to use GPIO2 for input (with a signal that is high by default or low by default while the chip is booting) or output (whether the output is driven high or low to trigger). Booting requires GPIO2 to be high but pulling-up disables it for various uses – especially detecting a high input signal …
Electronics reminder snippet: Pull-down an IO pin with a transistor
NPN – eg 2n3904, 10k on base, 1k on collector Use when the IO-pin has to be up by default PNP – eg 2n3906, 1k on collector Use when the IO-pin has to be down by default, eg IO2 on ESP8266 for boot conditions Make some notes about what happens, and some code for an …
Operator Priority in the C Programming Language and other stuff
Priority Symbol 1 ++ 1 — 1 () 2 ! 2 (typecast) 3 * 3 / 3 % 4 + 4 – 5 <, <= 5 >, >= 6 ==, != 7 && 8 || 9 all assignment operators One restriction on the switch expression is that it must evaluate to an integral type (int, char, short, long, long …
House DC Power
Make a board as per these PDFs Make aluminium bits to secure PSU. Mount the PSU in the wooden board. 3D Print fuse holders as per this STL Mark copper strips as per this DWG and these photos Drill 1.5mm holes from the marked side Drill 3mm holes in the 12mm pieces – slowly so …
WiFi-enabled AC Light Switch
A light switch that can be incorporated into a 2-way household switching circuit to add WiFi control while leaving the existing switching working in a way that requires the user to have no knowledge of the WiFi switch and allows installation using wiring conventions that are recognisable to anyone familiar with traditional 2-way switches. Troubleshooting …