Whoever invented this method must be a genius. This was a portable calibrator for high-voltage partial discharge testing. Because of HV, it was battery powered and insulated from the mains. But sometimes the test signal needs to be phase-locked to the 50/60 Hz AC mains frequency, and the solution was:

“with a photocell that synchronizes the instrument with the ambient lighting of the laboratory.”

#electronics

@niconiconi

That won't work with LED lighting though.

But I guess nobody thought people would be crazy enough to stuff a rectifier into every lightbulb.

@argv_minus_one It was written before LED lighting was invented.

@niconiconi
Just make an led that flickers the light in time with the mains frequency on purpose 🤪
@argv_minus_one

@pixx

I have a string of LED Christmas lights that flicker pretty hard. I assume they're just wired in series directly to mains, with no rectifier. So, it could use that!

@niconiconi

@argv_minus_one
I... wait you can do that

That makes sense

But also jfc why
@niconiconi

@niconiconi huh! That is brilliant, but I wonder if it got caught out with 3 phase lighting in commercial/industrial buildings, or if the different locations of the lights on different phases, was enough flicker to latch on to. That is a brilliant solution though. :-)

@khm
But

It's going into a diode

So yes you are??
@argv_minus_one @niconiconi

@khm

Plus the circuit was made in china so it arguably IS a commie rectifier!!!1

@argv_minus_one @niconiconi

@khm

They would blinkenlight at a steady 60Hz though. 🫤

@pixx @niconiconi