[WIP] 17mm DD+single-7135 driver / single sided / Dual-PWM

I changed to 240, offtime is much quicker, thanks.

I tried fastpwm and phase correct, both had buzzing.

So a low fuse of 0x65 seems to work to get rid of the buzzing. Any bad side effects from that?

If I understand correctly, that will change the PWM speed to about 1.2 kHz or 2.4 kHz… which is much easier to see. Even 4.5 kHz bugs me; I can’t not see it strobing unless it’s at least 10 kHz or so.

But if it looks fine to you, then it sounds like you’ve found a solution.

Sorry, I don’t keep track of the fuses. Can you fill me in on how that is different from the normal low fuse we use?

This page indicates that the low fuse gives a 14KH pwm github

But your right, using the light to illuminate the shower shows the pwm pretty bad.

I wish mine DID whine, then it’d double as a mosquito repellent. :slight_smile:

Hmm. I’m not positive, but I think if the PWM is really easy to see it’s probably not 14Khz.

I got the 1.2 / 2.4 kHz thing from the header comment in a STAR firmware file. I don’t know if it’s correct. :slight_smile:

In any case, the shower is actually pretty bad at showing PWM. The reason is because water droplets change shape as they fall, and small droplets change shape very quickly. So, the droplets will appear to flicker even under a constant-output light.

To test PWM I recommend quickly waving a white notecard (or other thin white stiff sheet) through the beam instead. Here are a couple images showing 488 Hz PWM versus 4.5 kHz PWM:

These images fairly accurately show how the lights actually look to my eyes under regular use… but I’m unusually sensitive to the flickering.

Good images ToyKeeper. I missed your last post and was pretty confused about bdiddle’s post after that saying that someone was right. Hence my rather pedestrian response.

bdiddle… the current firmware can be confusing to setup. Please post (not here - use somewhere else like pastebin or whatever you want) examples of you the entire program you used with Phase Correct and then with Fast PWM. It’s reasonably possible that you were not actually making the changes correctly.

TK, if you don’t mind will you please share the camera settings you used to determine those PWM’s?

So many variables with shutter speed, wondering how you got there. (I can freeze a high speed object, or make a snail look fast, depends on what I’m trying to achieve) Point being, how do you do the math after determining shutter speed.

I have found that with all the road construction in my area there is always dust in the air, this dust will show PWM quite well. I would imagine snow flakes would too. (not like I have those to shoot, it was around 70º today)

I wonder what settings it would take to show the faster PWM? Might be fun trying, I’d like to see what some of mine are actually doing but need some info. :wink:

Thanks

Edit: Isn’t it also pertinent to establish speed of the card in fps to get an accurate frame count?

Oh, um… I didn’t.

I measure PWM speed with a very small microphone and a guitar tuner app called PitchLab. When the pulsing is audible, the sound is by far the easiest way to get the frequency.

For some reason, most lights will get louder when they’re aimed point-blank at fabric. I don’t know why that happens, but it’s pretty helpful for measurement.

The pictures are just to give a rough idea what the resulting beam looks like, and how to visually check for PWM. I can only get a ballpark idea what the speed is through visual means. This is at least enough to sanity-check my sound-based measurements though.

I haven’t found airborne particles to be very useful for PWM. For example, this ice fog was shot with a 4.5 kHz PWM light. The particles were small enough to hang in the air instead of falling, and they showed no sign of flickering in the camera as the wind blew them around.

(click to enlarge)

+1
All the way from stable moonlight modes to direct drive with huge trace widths and many vias, on a one sided board.

I posted a pastebin of the code I am using in the Star firmware thread, here

toykeeper:

http://en.wikipedia.org/wiki/Photoacoustic_effect

try black fabric, it should be louder

thats a cool idea about the guitar tuner app.

Annother thing about the large copper area is that it reduces unwanted high frequency effects. It stabilizes ground at high frequencies with the capacitance between the layers.

That’s one of the coolest things I’ve seen in a long time. I had no idea it was caused by the dark fibers rapidly absorbing and releasing heat.

Now I really kind of want to make a firmware which will play tunes when aimed at black fabric. :slight_smile:

Do it :slight_smile: it would amazingly cool to be able load an midi file in to a firmware and have a hidden mode that plays the lights theme song :wink:

Not only disco modes anymore but an actual music producing disco mode :smiley:

Although i suspect something like that would take up alot of room in the attiny, but with all these new bigger attiny’s being discussed maybe someday it could be possible……

It’s cool, but with all the floppy drive symphonies and Tesla coil synthesizers, I think it’s already well-trodden territory. I think I’ll try to focus on making more useful stuff instead, like that off-time dual-pwm firmware people keep requesting.

Yeah you are right of course :wink:

But if you would just happen to run out of useful ideas, remember the one about the disco modes that actually sings :wink:

People might be surprised by an infrared flashlight with good throw doing that.