We keep hitting the same wall in maker projects: the reference material is either a 900-page datasheet, a decade-old calculator on a domain that now sells something else, or a forum thread with three contradicting answers. So we started building the tools we needed — free, no signup, no tracking. Here's the set and what building them taught us.
The tools
ESP32 DevKit V1 pinout (38-pin) — interactive per-pin reference with the warnings the datasheet buries: GPIO 6-11 are wired to flash (using them crashes the board), strapping pins (0, 2, 5, 12, 15) get read at reset, and GPIO 12 pulled high can stop 3.3V flash boards booting entirely. Per-pin anchors so a forum answer can deep-link exactly the pin in question. Prints clean for the bench.
ESP32-C3 SuperMini pinout — the $2 RISC-V board's own traps: GPIO 2/8/9 strapping, the flash bus at 11+, and why "my board won't flash" is almost always BOOT pulled by your circuit.
Resistor color code calculator — 4/5/6-band decoder with tolerance range and nearest E-series value. The result is saved in the URL, so pasting it into a forum answer reproduces the exact numbers.
IoT battery life calculator — the "how long will my ESP32 run on this LiPo?" tool, duty-cycle aware with deep-sleep presets. This is the one we couldn't find anywhere: generic battery calculators don't model wake/sleep cycles.
WS2812B / NeoPixel power calculator — PSU size with headroom, fuse rating, injection points. Realistic 20mA average vs the 60mA worst-case toggle every LED-strip thread ends up re-deriving.
Voltage drop & wire gauge — 12V wiring with the 3% rule, round-trip modeled. 5A over 5m of 18 AWG is 9.6% drop — the calculator says undersized before the LEDs do.
All six (hub): tinkernews.github.io/tools
What building them taught us
Unit bugs hide in plain sight. Our battery calculator was 1000x off on first build — milliseconds converted to seconds where the formula wanted hours. The fix was boring; the verification was not. Every calculator now gets click-tested against hand math before it ships.
Shareable state is the killer feature. Forum answers need a canonical URL that reproduces numbers. Putting the inputs in the query string turns every answer that cites the tool into a permanent, verifiable reference.
"When not to use this" earns citations. The battery calculator publishes its assumptions (regulator quiescent current, cold-weather loss, retry storms) and says when to trust it instead. That's what makes writers comfortable linking a tool.
Safe-GPIO warnings are content. The pinout pages get read because they say "never use GPIO 6-11" at the top, not in a footnote. The warnings are the product; the pin grid is the reference.
We run TinkerNews, a free weekly roundup of DIY electronics builds — these tools came out of the issues. If any of them are wrong, tell us and we'll fix that first.
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