Scrood indeed, but the good news is that Lowes and Home Depot (if they
are carrying the same type) may be big enough to be susceptible to
pressure. What these systems are doing is contrary to FCC regs, and the
RFI people at ARRL HQ (Ed Hare, W1RFI, is very knowledgeable) may be
willing to get involved. A few years ago, they scored a notable success
by getting the makes of the Homeplug LAN hardware to notch out the ham
bands.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 3/12/2013 12:27 AM, Mike Ryan wrote:
The box that these lights come in from Lowes says they are LED
lights. I bought one today and I am sending it to a friend to take a
look at along with a power supply. He wants to look it over to see
what can be done. But for now it appears that I am scr...d, blued, and
tatooed.
-M
-----Original Message----- From: Dale
Sent: Tuesday, March 12, 2013 12:21 AM
To: ka5s@earthlink.net ; rfi@contesting.com
Subject: Re: [RFI] Cree LED Bulbs?
Cortland, Mike, Kurt, and All,
If you go back to my post of a few days ago, it sounds as if I may
have scored a direct hit (by dumb accident) on this system; after
careful reading of Mike's information, it does sound like the
manufacturer is using a simple, iron core transformer to go from 120
VAC to 12 VAC. That's the good news.
Now, one thing I have not seen Mike comment on is if the devices
inside those lamp heads are bulbs or LEDs. If they are LEDs, I can
tell you that there are several manufacturers out there making
specialized ICs that serve as the constant current controllers for
LEDs. If they are bulbs, then I agree with Kurt's comments about bulbs
not caring if they get AC or DC. Either way, the picture I am getting
is that we have a low voltage, relatively high current wired
distribution system that goes from the step-down transformer to the
individual lamp heads. The problem may well then be what's inside
those heads, particularly if the lighting devices are LEDs.
Since cost is always THE driver these days (sad, but true), I can tell
you that I have been shocked by the number of app notes I have seen
from the LED constant current guys about circuits to use their ships
and in which there is little or even NO suppression of switching noise
on the input side of the device. Some of these chips are meant to run
on low voltage AC input, and then the constant current controiller is
a specialized switcher that outputs DC to the LEDs. So, the bad news
is that my "guess" about each lamp head containing a small switcher
might be correct. If it is, wow - what a mess!
-----Original Message-----
From: Cortland Richmond <ka5s@earthlink.net>
Sent: Mar 11, 2013 9:21 PM
To: rfi@contesting.com
Subject: Re: [RFI] Cree LED Bulbs?
On 3/11/2013 2125, Cortland Richmond wrote:
On 3/11/2013 1952, Mike Ryan wrote:
The landscaping lights turn out to be 12 volt AC powered and not 12
volt DC powered. All the suggestions about a car battery and/or an
Astron or other linear power supply now go out the window. -M
But the converter is still very likely a switch-type converter;
modern-day efficiency rules often rule out transformers on account of
core losses.
Cortland Richmond
KA5S
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And even if it does use a linear 12VAC transformer, the LED's themselves
require a constant current source -- and probably incorporate switching
regulators at each fixture. Have you contacted the system maker?
Cortland
KA5S
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