Electronics > Beginners
Why does this LED blink?
Lucky-Luka:
Hi all
I was looking at different solutions to let a LED blink on YT.
I found a strange one that I haven't understood...
In the comments several people mentioned an avalanche effect of transistors... Is it related to the case? What is it?
Cheers
Nerull:
The capacitor slowly charges though the resistor until the transistor goes into reverse breakdown, then discharges through the transistor, which then turns back off and starts the cycle again.
Zero999:
It works because reverse biased transistors work like spark gaps, but at much lower voltages. Here's a more comprehensive study.
http://www.kerrywong.com/2014/03/19/bjt-in-reverse-avalanche-mode/
Oh and this is the simplest way to make an LED flash.
https://www.tme.eu/gb/details/l-56bsrd-b/special-effect-leds/kingbright-electronic/ ;)
Lucky-Luka:
Doesn't this circuit damage the IC?
I would expect a current that would have destroyed it as in a normal diode.
It looks like the internal behaviour is different.
Is it possible to replace the IC with a zener diode?
Cheers
Lucky-Luka:
Another question: why 12V?
Am I wrong or the reverse breakdown voltage isn't mentioned in the datasheets?
Cheers
Navigation
[0] Message Index
[#] Next page
Go to full version