[Michael Kleinigger] posted a lengthy discussion on Pulse-Width Modulation that goes beyond the traditional beginner tutorial. He starts a bit of background info on PWM and a tip about using a camera to judge frequency and duty cycle of LEDs. From there it’s down the rabbit hole with some testing of power-loss versus frequency.
When you change from frequencies of 50 Hz to 1 MHz how does the parasitic power loss from switching affect the overall efficiency of the circuit? It turns out there’s a rather large amount of loss at the highest level, around 1.5 mW. The greatest balance of low power loss and elimination of flicker seems to be right in the 300-500 Hz range.
It seems that the site that the link refers to is permanently down. Here is a link to the article from the Wayback Machine (archive.org) as it existed on September 25, 2010:
http://web.archive.org/web/20100925053843/http://grieg.gotdns.com/blog/?p=188
All the images are broken and the formatting looks terrible, but the text of the article is there.
Thanks for the reminder Forrest… my dynamic DNS service decided not to be free anymore, and ultimately stopped forwarding. The article is still live and in its original form here: http://www.nlvocables.com/blog/?p=188
Thanks for the reminder Forrest. My dynamic DNS service decided to no longer be free… The original article can be found here: http://www.nlvocables.com/blog/?p=188