Syd Rumpo wrote:


Thermostat controlled flasher is probably the exact description. It
happens when LEDs are driven straight from batteries too, and is
probably the bond wire heating and cooling making intermittent contact
at a few Hz.

I have a cheap LED torch which uses nine parallel connected white LEDs
running directly from 3 AAs. After a battery replacement, one is out,
four flash at different rates, and four are on.



** Ahhh - so you have seen it really happen too !!!

Bit like sighting the Loch Ness Monster.

Bonding certainly seems to be involved and LEDs are very sensitive to high temps - way more than silicon semiconductors.

Gallium arsenide is even whimpier than Germanium, lifespan deteriorating quickly above room temp.


..... Phil