Thank you @6by9 and @fchk!
This explains it. I guess the concern over reducing drain on the PI by switching the 3v3 voltage to the breadboard with other GPIO pins connected was a bad idea. However, as the result of the bad idea, and a red LED, learning occurred (and any day that happens is a good day). The ADS1115 and MCP3008 chips draw mere microamps just sitting there, so there is no real need to for the switch.
I guess the rule is to isolate any circuitry with significant idle draw to its own little power-area on the breadboard and switch that if needed rather than the whole breadboard. Lord knows the ADS115 and MCP3008 chips which have sat powered next to the Pi Zero 2W for years before the switch idea came to mind show they certainly don't mind remaining powered continually and put no adverse draw on the Zero 2W.
Thank you for the lesson.
This explains it. I guess the concern over reducing drain on the PI by switching the 3v3 voltage to the breadboard with other GPIO pins connected was a bad idea. However, as the result of the bad idea, and a red LED, learning occurred (and any day that happens is a good day). The ADS1115 and MCP3008 chips draw mere microamps just sitting there, so there is no real need to for the switch.
I guess the rule is to isolate any circuitry with significant idle draw to its own little power-area on the breadboard and switch that if needed rather than the whole breadboard. Lord knows the ADS115 and MCP3008 chips which have sat powered next to the Pi Zero 2W for years before the switch idea came to mind show they certainly don't mind remaining powered continually and put no adverse draw on the Zero 2W.
Thank you for the lesson.
Statistics: Posted by drankinatty — Fri Oct 24, 2025 11:37 pm