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On Mar 31, 12:34 am, wrote:
Try hehttp://ogmtechnical.blogspot.com/
Thanks for that link. Speculating between the lines and being a tad
skeptical of company self-reporting it sounds like they may have unit
to unit differences in RFI and hence a manufacturing/QA problem. PWM
regulators are made in the gazillions for the automotive market. As I
recall the gent in the PS letter was quoted as saying (more or less)
"gee we've installed countless LEDs in cars and we never have had a
problem with RFI there, it must be a user thing."
It most certainly is.
But, boats aren't
cars. Rather like gasoline engines that need to be modified for
marine use with things like spark arrestors and bilge blowers because
of potential problems in boats, LEDs for marine use should take
particular care with RFI because of potential problems.
No, the wiring in boats should be done as carefully as in cars. If the
regulator can pass FCC emissions for cars, it should be passing for boats.
But in some cases they don't because the wiring in too thin and too long for
the intended use. The supply feed wires, rather than being low impedance
become a high impedance (inductive) and do a great job of acting as an
antenna for any noise on them. For the most part boat wiring is the
sloppiest crap in the world. Here are some boat wiring tips:
1. Use adequate gauge wire. The feedline resistance, depending on the
current it carries, should be 1/2 ohm or less.
2. Use twisted pair type wiring to reduce emissions and susceptibility.
3. Don't dump all you ground currents into the same wire. Use a single
ground wire for each fixture. Don't daisy chain grounds. Keep the ground
impedances low.
4. Solder, don't crimp!
5. Put ferrite chokes at the electronics box to reduce conducted EMI. Shunt
the supply lines with filters caps were practical. Increase the common mode
rejection on supply lines.
6. Don't loop wires into coils, keep paths as short as possible.
PWM
regulators are great but because of their timing circuitry are
potential RFI emitters.
It's not the regulator that is emitting, it is the wiring feeding into it.