From aa4bc7ae1ea14096fd4e4b9d96714dd93b272063 Mon Sep 17 00:00:00 2001 From: The_miro Date: Sun, 2 Aug 2026 01:20:59 +0200 Subject: [PATCH] Make the min_brightness step actionable, and cap max_brightness MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit min_brightness was one line with no procedure. Setting it to 1 is wrong — triacs stop latching reliably at very low phase angles, so it presents as flicker rather than a dim glow. Document walking it down to instability and backing off a step, since the usable floor is fixture-specific. Also add max_brightness, which matters more: filament life goes roughly as V^-13 against light as V^3.4, so running at 95% roughly doubles lamp life for ~15% less output. Worth having on a fixture whose lamp type may be discontinued. Co-Authored-By: Claude Opus 5 --- docs/stage-light-dimmer.md | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/docs/stage-light-dimmer.md b/docs/stage-light-dimmer.md index 82982b3..82e3f8d 100644 --- a/docs/stage-light-dimmer.md +++ b/docs/stage-light-dimmer.md @@ -172,11 +172,22 @@ One setting genuinely matters: means a power blip or a Z2M container restart brings a 250 W stage lamp to full brightness in an empty room. -Two worth doing: +Three worth doing: -- **Lower `min_brightness`.** Defaults are tuned to stop LEDs flickering at the - bottom of the range. A filament dims smoothly to near-zero, so dropping it - recovers the usable low end. +- **Tune `min_brightness` by walking it down.** The default is set to stop LEDs + flickering at the bottom of the range, and a filament doesn't need that + protection — it dims smoothly to near-zero. But don't just set it to 1: at very + low phase angles the triac stops latching reliably, which shows up as flicker + or dropout rather than a dim glow. On the Z2M device page, lower it a step at a + time until the lamp goes unstable, then back off one step. That point is the + real bottom of the usable range, and it's fixture-specific — worth writing the + final value down. +- **Consider capping `max_brightness` around 95%.** Filament life is brutally + sensitive to voltage: roughly `life ∝ V⁻¹³` against `light ∝ V³·⁴`. Running at + 95% buys about **double the lamp life for ~15% less light** — a good trade on a + fixture whose lamp type may well be discontinued (§6). At 90% it's roughly 4× + life for ~30% less light, if longevity matters more than output. Rules of + thumb, not exact, but the direction is very strong. - **Pass `transition: 2` in `light.turn_on` calls.** Ramping over a couple of seconds cuts the cold-filament inrush, which is the biggest single wear event on the lamp and the main stress on the triac.