I recently bought several Cree 815 lumen lamps with Edison style bases as replacements for some compact fluorescent lamps (which were replacements for incandescent lamps). Anyway, the Cree lamps have an internal switched mode constant current power supply to adapt the 120 VAC 60 Hz clean sine wave mains power to DC for the LED array. This SMPS probably can accept some pretty distorted power and yet hold the LED load at proper current.
However, I also have a duty cycle electronic dimmer on this circuit, creating a delayed turn-on (on both half cycles) sine wave. Interestingly, the Cree SMPS somehow tracks the amount of sine wave delay and lowers the LED current so as to mimic how an old incandescent lamp would dim. I'm curious how the Cree SMPS manages this, so does anyone have a link to an explanation of how a dimmable LED SMPS works or even what the circuit looks like? Ed Price WB6WSN Chula Vista, CA USA - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
