Hi there, I think the link above is missing.

frank

Link missing

No me too. links broke. :(

Not just you – hopefully fixed soon, I’d like to read this :)

You may get a wonderful efficiency at 300-500Hz, but you may also get significant side-effects such as audible noise when you drive anything bigger than an LED. For this reason, it is sometimes better to run PWM at frequencies higher than 20kHz

PWM makes the best music…

I ♥ LFOs

Yeah link no workey for me either.

PWM depends on duty cycle and frequency, so maybe a nice chart comparing the two would be good to have (???). I dunno….methinks this has to be played with for each application, but some handy charts for LEDs, 5V motors, and other commonly driven things might be nice…

As for the sound issue…yeah…sometimes it’s nice to actually hear your circuit working.

500Hz… Depends on what you are driving. I can see an led flickering at more than 2KHz as I was curious one day after being irritated by the light on my xbox 360 controller (which happens to flicker at 2KHz 64% duty cycle). Does any one else notice the flickering in the new LED brake lights on modern cars?!? This drives me nuts when I am driving at night. ~Aaron

Aaron – I too can see the brake lights on LED using PWM… it does get annoying. If you’re like me, I can also tell when a DLP projection screen/ tv is being used, as the white objects look like a rainbow due to the color wheel… it gets pretty hard to get used to…

http://en.wikipedia.org/wiki/Flicker_fusion_threshold
Most people can’t detect flicker at 100 Hz.

I propose a simple A B test to see how high you can detect the frequency.

@Travis, agreed.

If people here claim they can see flicker above 100hz, the flicker they’re actually seeing is probably due to noise and under 100hz.

@Travis and andrew,

Yes, I’ve read in places that 60Hz is the cutoff for most people. And I think that’s about right, assuming you’re starting directly at the LED without any relative motion. However, when you start to move your eyes across the LED or if the LED is moving, you may notice the flicker, maybe even up to 2kHz depending on the speed of the motion. This is why POV displays work.

@alankilian

Speaking of 5Mhz modulations, I’ve been hearing lately about research into high-speed data transmission using ambient LED lighting. In the future, when incandescents and fluorescents are replaced by high-intensity LEDs, your laptop might actually connect to the internet via the lights in your room; they’ll be doing double duty – lighting the room and transmitting data via high-frequency modulation. Pretty cool, eh?

the 360 controller LEDs don’t flicker, they’re either always on or always off. The 360 ROL does flicker, and it’s a hell of a lot slower than 2kHz.

There is no way you can see a 2kHz flicker on a stationary light. hell, I don’t think I’d believe you if you said 200Hz.

CRT monitors have an vestigial glow but LED, as I believe don’t. Then LED flickering might be visible in higher frequencies.

and don’t put all your heavy-load PWM channels on the same phase unintentionally.

Efficiencies from protoboards shouldn’t be related to circuit boards. Protoboards are full of capacitance. Also, lead inductance can come into play with the through-hole vs surface mount components.

@allyouguystalkingaboutLEDflicker

Just like the old LED clocks, you can kinda tell when things are pulsed, even over 60hz.

One trick for detecting this is to motorboat your lips. The displays will vibrate…:)

Hey can anybody tell me the name of the white thing this guy has put his components

@mike

Thank you for the info this is helpful but i mean the base bit, with the red and blue lines on it
that all his things are stood in/on i want to start out and im looking for somewhere to buy one from but need the name first lol

Lol, right, the protoboard. Thanks Karl!

Now you all know you are not allowed to use PWM dimming on LEDs because you may get your ass sued by Color Kinetics. They own a patent on this shit and are quite liberal when it comes to handing out the lawsuits.

@ johny

im no lawyer but last i checked unless your building their circuit they cant sue or if they do you can get it thrown out of court. lets face it you cant patent the action of pwm but you can patent the circuit. just build a different one.

The discussion of power consumption and frequencies reminds me of Tesla’s work with high frequencies

@Alex

That’s a 5V, 2.5F supercapacitor from NessCap: http://parts.digikey.com/1/parts/90426-capacitor-ultra-2-5f-5-0v-radial-emhsr-0002c5-005r0.html

Whoa, yea 400F is pretty impressive… also incredibly expensive I’m sure. Looks like the largest one DK has in stock now is 4000F, 2.5V, for a mere $250. I want.