Home |
Search |
Today's Posts |
#1
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
Before I spend $60 to$80 to replace the masthead tri-color bulb with an LED
equivalent, I am wondering what the consensus is here about interference between LEDs and VHFs (or other electronics). Are there certain LED lights that are superior or worse in this respect? What in-use experience can anyone relay? -- Good luck and good sailing. s/v Kerry Deare of Barnegat http://home.comcast.net/~kerrydeare |
#3
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
"Roger Long" wrote:
I've had no problems with my LED anchor light and have gone to all LED's this season except for the bow light which is only on when the engine is running and the spreader light because I want that to be really bright on the sails. It's as much for increasing visability at night if someone doesn't seem to see me or answer the radio as for deck light. The problems seem to have been with the early crude LED's that were meant to plug into the original bulb sockets. I would be very surprised if there were problems with the units such as Aqua Signal and Hella that are designed from the start as LED fixtures and have been through regulatory approval processes. Go for it and don't worry about burned out bulbs and power draw again. BTW, no one seems to make a good, compact, bright, spreader light. I put on one of an $11.00 pair of small auto fog lights with a small hole drilled in the clear lense the first year when money was tight. I replace the rusting casing every 2 - 3 years. I want to put something more permanent and nautical on this year but I can't find anything I like better. Don't know if they meet your "compact" requirement, but go to Hamilton's and look at the Jabsco floodlights. I am using 2 as "spreader" lights on Barbara and they give lots of light on the deck. Cheers Michael Porter Marine Design mporter at mp-marine dot com www.mp-marine.com -- Posted via a free Usenet account from http://www.teranews.com |
#4
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
Roger Long wrote:
... I would be very surprised if there were problems with the units such as Aqua Signal and Hella that are designed from the start as LED fixtures and have been through regulatory approval processes ... I am hoping to replace only the bulb itself rather than the entire fixture, an Aqua Signal Series 40 Tricolor/Anchor combo. Is the LED for this known for interference? -- Good luck and good sailing. s/v Kerry Deare of Barnegat http://home.comcast.net/~kerrydeare |
#5
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
On Mar 30, 1:44 am, "Armond Perretta"
wrote: Before I spend $60 to$80 to replace the masthead tri-color bulb with an LED equivalent, I am wondering what the consensus is here about interference between LEDs and VHFs (or other electronics). Are there certain LED lights that are superior or worse in this respect? What in-use experience can anyone relay? It will always be at least a potential problem with PWM current regulators. Shielding that works adequately in automotive lights may well not be good enough for marine service. "Practical Sailor" has received complaints as recently as this year. I'd suggest using a portable AM radio to test your unit for RF before installing. If you want to avoid the PIA of testing you could insist on lights that are not PWM regulated. An acquaintance of mine runs a shop in Fiji that makes LED lights. Obviously, he's an interested party but I think he is very, very honest. Here is his description of the problem: http://www.bebi-electronics.com/regulator.html. -- Tom. |
#6
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
On Sun, 30 Mar 2008 16:29:05 -0400, wrote:
wind my watch, even if it was already broken. I have ,a Rolex mechanical, not electric, watch that has to be wound. Rolex invented the self winding watch in 1939, but mine doesn't. There are many that I wouldn't trust to wind it. It is actually easy to screw up, unlike with most mechanical watches. Casady |
#7
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
On Mar 30, 10:29 am, wrote:
A potential problem is not a problem. That's like saying all gasoline powered cars have the potential to explode in a ball of flames at any moment. How many manufacturers of LED units are using pulse width modulation regulators, and of those, which ones ACTUALLY have a problem? When it comes to technical information that is trustworthy, I wouldn't let the amateurs at Practical Sailor wind my watch, even if it was already broken. Whatever. PS is perfectly capable of passing on reports of problems. You might look over http://www.ssca.org/DiscBoard/viewto...t=2687&start=0 or do a little search. -- Tom. |
#8
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
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." 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. PWM regulators are great but because of their timing circuitry are potential RFI emitters. By the way, some remarks that Roger made have reminded me that changing the bulb in your nav lights from the manufacturer's tested type to anything else will take the lamp out of compliance. I'm not lawyerly enough to know what having non-USCG approved lighting does to a skipper's liability. It is likely that many LED bulbs will not comply with Annex I section 8 despite being visible at the ranges required by rule 22... It's also likely that USCG stamped LED lamps don't meet annex I.8... -- Tom. |
#9
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
wrote in message ... 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. |
#10
posted to rec.boats.cruising
|
|||
|
|||
LED Interference
wrote in message ... On Mon, 31 Mar 2008 12:19:50 -0700 (PDT), " wrote: 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. Sounds more like there are variables in how they are installed. Bingo! We have a winner! 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." 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. PWM regulators are great but because of their timing circuitry are potential RFI emitters. The current used to power an LED mastlight is TINY. Even if the regulator WERE a bit noisy, it would be so weak that it likely wouldn't have any effect at all unless maybe the regulator was mounted directly on the antenna whip. The regulation in my anchor light is completely surrounded by the grounded metal bayonet base. If the switching signal (PWM) is run into an inductive load in a poorly designed circuit you could have tens or even hundreds of volts as a transient signal. It's not the current but dI/dt that makes the voltage. One does not need an antenna to radiate. A plain old wire can work just fine. Since this is all so variable, it points right at the installation factors. By the way, radio amateur QRP distances show over 1,000 miles range with a single NAND gate as the output driver. Figure PWM waveform is 5V @ 5mA = 25mW-- 14 dBm into 50 ohm. VHF radio sensitivity typically 0.25 uV into 50 ohm ---1.25e-15 Watt or -120 dBm. Say the PWM operates at 100 kHz so the 1500th harmonic has to be down -134 dB to be undetectable on the VHF. The Fourier expansion of a square wave PWM shows the harmonic coefficients decreasing as 1/n, n being the harmonic number so the VHF in-band harmonic is 1/1500 of the original signal or about 33 dB down. That leaves about 100 dB of required attenuation (if all the DC input power were radiated) not to interfere with the VHF. FCC requires the harmonics to be much lower, which they are in order to comply. Automotive testing is rigorous and thorough and it takes a real screw up to get the thing to radiate and cause interference in the boat. The lesson here is if you don't understand electrical installations, hire an experienced (even licensed) technician to do the work It may save your life. By the way, some remarks that Roger made have reminded me that changing the bulb in your nav lights from the manufacturer's tested type to anything else will take the lamp out of compliance. I'm not lawyerly enough to know what having non-USCG approved lighting does to a skipper's liability. It is likely that many LED bulbs will not comply with Annex I section 8 despite being visible at the ranges required by rule 22... It's also likely that USCG stamped LED lamps don't meet annex I.8... The USCG doesn't test devices and approve them. They publish standards, and a laboratory tests your product and charges you a fee to attest that it meets the standards. If you have an unapproved device and it becomes an issue in court, you can still retroactively have the device examined and declared compliant. Good info on the retroactive part. You can't do that for FCC. A kerosene lamp is perfectly valid as an anchor light as long as it meets the standards. No actual "pre-approval" is needed to use it. You just have to have confidence that it can meet the criteria. My LED anchor light is USCG approved because I say it is. No one has asked me to prove it, but I'm sure I could hire someone to validate my claim if it was ever needed. Meanwhile, just hope that when you have to defend your unit with a stamp of approval on it from some lab, the opposition doesn't take the wind out of your sails by claiming it was partially obscured by a blob of bird **** on one side and therefore didn't meet the standards at the time of the incident. Let's put windshield wipers on all navigation lights! |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Depthsounder that uses other than 50 or 200 kHz? Transducer interference? | Electronics | |||
Laptop SSB interference | Electronics | |||
Electrical interference | Boat Building | |||
Fluorescent interference | Electronics | |||
Interference from autopilot | Electronics |