DICEGEORGE wrote:

Decades ago I hotwired a diode across a switch
which cut out half the AC signal when switched off,
would this work with modern lights?

Likely to vary on anything not incandescent ...

it could just carry on at full brightness if the internal Rs and Cs
allow it to pull enough current during the half wave that remains

or they might become horribly flickery

or you might end up overheating two out of the four diodes in the lamp's
bridge rectifier if they're run close to max