Proton BASIC Community

Quote from: John Lawton on Nov 28, 2024, 11:03 AMLEDs are amazing in that they'll emit visible light with just a sniff of current and/or a very short pulse of current so really smooth PWM dimming at the bottom end is hard to do.

On a side note, recently the municipality changed the old sodium street lamps with LED lights and it is terrible.

It is like there's no light flooding at all. The border line between shadow and light is so sharp that few inches away from the line and it is pitch black whereas with the old sodium lamps you can still read in the shadow behind a tree trunk that grows in the front yard.

I don't know what is causing this effect but the old sodium lamps created more reflected light in the air.

On a related note: when I look at some LED-driven things, like the button you press to turn the road crossing signal to STOP, if I scan my eyes left and right I see a line of red dots. This is obviously because the LED is driven by PWM.

But hears the thing, I read somewhere that the human visual system "turns off" the visual processing while your eyes are moving, to avoid the same blurring that would happen with say, a camera with a slow shutter. Perhaps there is something wrong with mine? Although I don't see blurriness (except after some G&T medication).

Am I alone in this ability to spot PWM?

Charlie

QuoteI want to add again.  LED lights tend to flicker at lowest settings, the higher the resolution, the less the flicker effect will be when it sits exactly on the edge where it switches down or up.

You can easy filter this out by making two limits (A/D count +- 2 or 5...) to compensate for the pot setting and the A/D reader, but other factors also plays a role, like the solar regulator switching on and off, and hence the LED's supply voltage change up and down, as well as other items working off the 12V can affect the same.  On brightest it is least visible, and dimmed has a larger effect.  Does not really bother, nobody sits and watch the light (except me) to see if and when it made a small flicker.
On the daynight lights I switch the light off completely every few minutes, read the LDR to see if it is dark or light, and switch the lights on again (if dark) and you cannot see a flicker.

Quote from: charliecoutas on Nov 28, 2024, 11:26 AMAm I alone in this ability to spot PWM?

Same here. Also it is quite annoying with the peripheral vision.

No, you are not that unique Charlie, just like everyone else

We can see things while we move, deer cannot, they have to turn their heads and stop repeatedly to keep looking at a moving object.  This movement often gives them away despite their camouflage.  The flicker can be because the light is switched on and off at a duty cycle, perhaps to save power.

As you said, the light trail is probably the same as a long open shutter filming cars at night.  Maybe your shutter time is a little longer than others
Not sure what the G&T medication is you refer to... Just hope the doctor didn't tell you to stop watching sequels

You can easily measure the frequency at which that light is switched.  One solar cell, an audio amp and speaker for audible and frequency meter and with a battery of course.  You'll be surprised at how high a frequency that solar cell can pick up light changes.  At light off the speaker is quiet, at full on the speaker is also quiet, but in between it moans.  Someone wanted a few of these "sensors" so of course I made myself one also.

"Not sure what the G&T medication is you refer to... "   Gin and Biltong soup. We have a couple of escapees from S.A. who run a cafe in our town. They put Biltong Soup on the menu, very tasty.

Quoteescapees from S.A.

Escapees is the right word.  Off late even the Africans want to go back to their countries.  Getting in is easy, getting out is not so easy.

Quote from: trastikata on Nov 28, 2024, 11:35 AM

Quote from: charliecoutas on Nov 28, 2024, 11:26 AMAm I alone in this ability to spot PWM?

Same here. Also it is quite annoying with the peripheral vision.

Some ~20 years ago there was a stationary 'persistence of vision' led sign at nightclub, behind the bartender. Normally it would just appear as vertical string of blue LEDs. But if you turned your head, you would see parts of text 'ABSOLUT VODKA' at corner of your eye.

It didn't work if you tried to watch it directly and on purpose. It only worked on peripheral vision. I told my two friends about it, but they couldn't see it and did not believe me. We probably looked like bunch of idiots shaking our heads.

Surely this is more about multiplexing than PWM.
This was common with early digital instruments with 7 segment displays where you had a single segment decoder with multiple digit drivers.  At any one instant there was only ever 1 digit driver enabled even if the display was 8 or more digits.  By turning your head you could sometimes catch a partial display as it multiplexed through the digits.

Quote from: david on Nov 29, 2024, 07:18 AMBy turning your head you could sometimes catch a partial display as it multiplexed through the digits.

Yes.  Our eyes perceive (or is it mislead) a lot.  Some people have their one eye tuned for looking near while the other see far.  The brain adjust to this, and they can then see near and far.

In this video 
(don't watch if you're sensitive to skeletons, rather go watch the violence in Disney cartoons)
https://www.youtube.com/watch?v=uZODBs5Z-zg
Unleash the Power of Skeletons
If you see any skeletons in it, you urgent need a vacation

Notice the effect the video have on your eyes vs when you pause it.



Below, inside an ESP32-S3.  The pins around the perimeter is hollow, likely to form a meniscus for solder to ensure connection.

Quote from: jaka on Nov 29, 2024, 06:45 AMSome ~20 years ago there was a stationary 'persistence of vision' led sign at nightclub, behind the bartender. Normally it would just appear as vertical string of blue LEDs. But if you turned your head, you would see parts of text 'ABSOLUT VODKA' at corner of your eye.

That is something I must try out sometime! A vertical row of LED's that could display text when ones head is turned at the correct rate; most interesting. Maybe ON and OFF in different colours. It would be interesting to see how long the string could be.

Quote from: ken_k on Nov 30, 2024, 11:57 PMThat is something I must try out sometime! A vertical row of LED's that could display text when ones head is turned at the correct rate; most interesting. Maybe ON and OFF in different colours. It would be interesting to see how long the string could be.

I have also been thinking to try make such thing. You can't make very long string. It was not possible to see the whole ABSOLUT VODKA at once, or at least I couldn't.

What you saw is the same as when a fan spins and you shine a strobe light on a blade.  It's a matter of timing.
So the strobe rate of the display and the speed you move your eyes will determine if you can observe any effects.

We have a bit of a heatwave.  Typing with mittens on 

I made an attempt to print two colours for a faceplate.  Previously I just printed the recesses and can be coloured with a permanent marker, but in theory this should work better.
Doesn't like small text, and these are 0.2mm, more layers will be better.

I shot four rats over last weekend, and another day before yesterday.  Rats have a way of announcing their presence, if you listen.  Don't know why they do it.  Perhaps a territorial thing.  That is how I knew they were there and I exterminated the whole family.  All were what I call milk rats, very small.  So I sent a picture and message to my so called friends complaining about the small rats and don't they have decent ones I can take out for them.  Looks like we have a shortage of large rats here, apart from all the other disasters.

I asked where Tim is.  Does anyone know ?

I had to loan a portable oscilloscope from someone a while back, so decided to rather get my own.  Here they are pricey, so it's off to China.
I ended up getting this one.

https://www.banggood.com/FNIRSI-1014D-7-Inch-TFT-LCD-Display-Screen-2-In-1-Dual-Channel-Input-Storage-Oscilloscope-Digital-Signal-Generator-p-1864812.html

And so far it works awesome.  Triggers easy and nicely visible.  I have a power bank to run it from (5V).
The only problem I see is the function generator does not have an amplitude adjustment.