Never saw the original post. There is a holding current in a triac, and once
the current drops below this a kind of Hysteresis occurs so you need to turn
it up to get it conducting again.
Brian

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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Rod Speed" wrote in message
...
Commander Kinsey wrote
Is it to warn you?

No idea what you are on about this time.
Even my toilet cistern can slow down smoothly.

Rather different technology. Many dimmers cant,
they cut off abruptly at the lower light levels.