Stoneridge Engineering Home |
Hi Jerry, With this simple circuit you won't have to worry about RFI or emissions filtering since nothing in your system will be creating any high frequency nastiness. However, since the LED's are directly connected to the incoming mains, there will be some safety consideratinos that need to be addressed. These would include the possibility of a person accidentally making contact with the mains, or fire hazard under abnormal operation/conditions. You can avoid some of these concerns by powering the LED's from a Class 2 current limited low voltage transformer and DC power supply - a "wall wart" - instead of directly off the line. Adding an electrolytic capacitor to filter the DC will reduce LED flickering a bit, but otherwise may not be necessary. If you intend to offer this as a commercial product, you may wish to contact an expert in UL/CSA requirements/verification. Good luck, Bert
: Hello Bert! Hey it's been awhile since I've written and I hope you've been
: well. I've got a new job installing high voltage high current sensors for
: utility companies using fiber optics to sense the magnetic field. Cool
: stuff. Anyways, What I'd like your advice on is I have a very crude ac/dc
: supply powering a string of led's. For instance, if the input is 120ac I
: have it going through a full wave rectifier and can power about 40 leds at
: about 28ma. My question is if I just use the rectifier and a 10-20uf cap
: to smooth out the dc, will it pass UL testing? I will have a UL rated 600v
: cable going into a small metal box with the hot going through a 500ma
: fuse. The box will be tied to earth ground and the hot and neutral will go
: to the input of the rectifier on a small circuit board and the unregulated
: output will of course go to my string of led's. Do I need to add a tank
: circuit or an emi filter? What about RFI? The led board will be mounted to
: a UHMW 1/4" mounting plate. Your help is of course greatly
: appreciated
:
Message Thread
« Back to index | View thread »