LED clipping only one lights up

[samhay]

The emitted photons will all be a similar colour, I suspect.

Yes - an LED will produce a range of wavelengths within its colour range. To be clear, when I wrote "visible photons" I meant those that actually escape from the LED (see my previous posts), not those that are in the visible light spectrum.

Most diodes emit a fairly narrow band of photons - a few 10's nm FWHM at most.
Your point about not all photons escaping the lens of the LED is a good one, but you will still have a few photons that do escape with very low diode conduction, you just need much more sensitive detection methods that the human eyeball to 'see' them - avalanche photodiodes are a good way of measuring them if anybody wants a bit of an off-topic DIY project.

Slacker - nice post.

[morten_beta]

@Kary

It does not say which LEDs I was using. But it's standard regular 5mm reds. With a series resistor at around 3K3 I get lots of clipping but asymmetrical and not without light.

@All

It's been really interesting reading here. I've learned tons!!!

[karbomusic]

@Kary

It does not say which LEDs I was using. But it's standard regular 5mm reds. With a series resistor at around 3K3 I get lots of clipping but asymmetrical and not without light.

@All

It's been really interesting reading here. I've learned tons!!!

Cool, I sort of suspected they were red due to popularity but wasn't sure. I still need to go back and test the green ones and a few others I have because I have a suspicion that those that don't illuminate when clipping may be outliers (If not then good as well but at least I know at a more precise level). In other words if that is the case then we should consider "seeing" the clipping as typical and not the exception for the most used colors because it reduces unknowns in troubleshooting and helps us all in a number of ways. I have a booster (the one above) where the clipping LEDs are indicators not intentional clippers. That project is exactly why I was more aware than I normally would be.  

I've certainly enjoyed the academic volley as well!

[deafbutpicky]

I'm coming from a different approach but have encountered similar behaviour, asymmetrical clipping when symmetrical was expected, and got hung up at the capacitor before the clipping diodes. It's somewhat of a clamping circuit if asymmetrical clipping
is involved and I think the output cap is recharging the source (here the op-amp out or collector) when it's expected to do the negative half of the signal. It's effect can be dampened by inserting a resistor between output cap and clipping diodes. I don't think it has too much to do with the type of diodes but with what's feeding them, or their feedback effect.
I'm sorry I can't explain myself clearly right now, just wanted to point at it...

[karbomusic]

Just checked 6 more colors...

Green clear
Green regular
Yellow regular
Blue regular
Blue clear
Orange clear

So far I still can't find any in my batches that clip before I can see them FYI. Will update when I get to test the remaining ones which is probably 4 or 5 more.