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Starburst lamp revisit 11 years later

🕑 Added 2024-09-23 15:50:22 +0000 UTC

Comments

Charles Bruckner

Well I tested with a DC supply and 15 of them work just fine. I set up my bench Variac and a full wave rectifier from 4 1N4007 for a DC supply with lots of ripple. And yes it made many of them reset back to red.

Big Clive

With a smoothed DC supply, a series string of slow colour changing LEDs will usually hold their colour. I think the main issue will be if the supply current is limited and you have more than one series string in parallel, since the string that currently has the lowest combined forward voltage will pull the voltage down and hog all the current.

Charles Bruckner

Just going to set up 15 of them in a bread board. and power them up on the bench supply.

Mark Warburton

I wonder how manufacturers manage to put 400V onto a tiny IC without the magic blue smoke emitting? It sounds too good to be true, but then these chips are pretty ubiquitous, so they must have figured out a way.

Alice Chapman

I suspect that they'll keep resetting to all red. But please take one for the team.

Charles Bruckner

I have some on hand, and if I remember correctly each board is 15 in series for a string voltage of 40v. I will do a quick experiment to see how the LED's I have will behave.

Big Clive

It would be quite interesting. But all the LEDs would need to be in series as the changing colours results in a change in voltage across the LED string meaning it's less suitable for wiring them in parallel.