The CFL's I've analyzed and disassembled have small switching power supplies, usually running around 40-50 KHz.
If you are a VLF/LF listener, you can see the emitted signals up through several hundred KHz. Many sidebands can be observed, at multiples of 60 Hz from the central frequency (which is unstable). Usually, though, not much can be heard about 1 or 2 MHz if your antenna is separated by a few tens of feet from the lamp. If you have a defective CFL, disassembling it can be educational. First, you will see many components stressed at or above their maximum ratings. I've seen some with the filter caps operated with voltage above the maximum rating. Second, it's not uncommon to see the PCB with holes and traces for EMI filtering, but the parts are not installed. I assume that the parts are installed in some prototypes to meet EMI specifications and then are omitted to save money. I don't believe the CE approval markings mean anything to the Chinese manufacturers. I've written a bit about CFLs at http://www.cliftonlaboratories.com/compact_fl.htm Jack K8ZOA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
