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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 9:02 am 
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tomp wrote:
LEDs can be run with a DC suply and a simple resistor. In that configuration you get a sort of constant current to the LED. That is not a very efficient way to do it and in addition, any changes in voltage will be reflected as changes in light output. Better LED light sources use a constant current supply that mitigates line voltage changes. Also common today are dimmable LEDs where a circuit inside the lamp looks at the RMS voltage coming into the powersuply from the dimmer and sets an appropriate current to the LED. BTW, The quality of that voltage to current conversion can vary widely depending on the quality of the power supply used.


My driveway lights have the kind of circuit you are describing. Not dimmable, but regulated.

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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 9:59 am 
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Tom: You seem to be talking about home lighting -- I am talking about a simple pilot light in an amplifier.

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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 10:31 am 
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SoundMods wrote:
Tom: You seem to be talking about home lighting -- I am talking about a simple pilot light in an amplifier.


The thread was started about a problem with LED home lighting...

Roscoe

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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 10:33 am 
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SoundMods wrote:
Instead of reinventing the wheel how about a shunt capacitor across the LED. It is a DC device and any AC component being introduced to it can be bypassed to ground out of harm's way.


The LED is on the DC side, I'm sure it has decoupling capacitors in place already. The problem is the noise coming out of the AC side.

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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 11:59 am 
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OH! Thanks Rosco!

I have an issue myself. The power supplies of these energy saving devices puts out a lot RFI. Since I get broadcast television over-the-air through an attic mounted antenna when my LED recessed kitchen fixtures are energized I loose two Washington D.C. channels -- 7 and 9. Although they are ATSC digital they got approval from the FCC to still broadcast on VHF channels. When the lights are on those channels just go black. My master antenna low-noise distribution amplifiers are isolated from the power line.

The RFI is blasting it's way through the antenna and the TV electronics can't decode what is messed up. All the other channels are not effected -- they are mostly UHF and seem to brush off the noise like water off a duck's back. The local channels 11 and 13 (also VHF) are nearby and can run over any noise.

And yet -- when I retrofitted to LED lighting I saw a substantial difference on my utility bills. So I deal with it. Money talks and bullshit walks.

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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 1:39 pm 
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DaveR wrote:
SoundMods wrote:
Instead of reinventing the wheel how about a shunt capacitor across the LED. It is a DC device and any AC component being introduced to it can be bypassed to ground out of harm's way.


The LED is on the DC side, I'm sure it has decoupling capacitors in place already. The problem is the noise coming out of the AC side.


The power supply in LED lamps may be having trouble filtering the AC side noise and passing it through to the LED or else the CC control circuit may be having trouble with the line noise. I have a number of LED bulbs in my house from Feit and other manufacturers that are very low cost and also lots of switch mode power supplies. I have not had any flickering with them. The only time I have had any flickering is when I'm operating the whole house on my backup generator and that is probably the regulator in the generator hunting when the load is low. Under high loads it goes away.

With all the electronic devices that are being used today in the typical home with almost all of them having input filters, line noise in general is greately reduced. I know that in the last 10 years I have had great difficulty using devices using PLC (power line communications) protocol because all the line filters in the various electronic devices filter out the HF communication signals superimposed on the AC line.


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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 2:16 pm 
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I have many switching PS in my home (two laptops, router, 3 wireless phones, TV, cable box etc etc) but was surprised that this lightbulb is so susceptible to switching noise? If all GE LED Reveal bulbs (a premium bulb) are going to flicker with a nearby Apple PS that GE needs to work harder at isolating their DC supply from home born noise.


On the plus side, I can now walk around my home and plug this lamp in to see if noise on the outlet is an issue, a cheap noise sniffer. :think:

But it certainly reminds us of how much noise is present in our homes and wires, not something we want in our audio systems.


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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 2:36 pm 
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My go-to for home lighting is Cree. They did most of the development and presented excellent white papers to the IES (Illuminating Engineering Society). I was a member in my past life, but unless Cree or Phillips were presenting the meetings were generally boring.

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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 4:14 pm 
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Another way is a true sinewave inverter and rechargeable batteries to take the system off the grid.

Just depends on the power requirements. I built one with a 2KVA True Sinewave inverter and 4-100Ah AGM batteries. About the same line distortion as my AC line in the house at 2% THD. Needed that for the single ended solid state setup years ago.

AC Power regeneration works as well.

My wife loves light dimmers. Ugh!


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 Post subject: Re: Switching PS issues?
PostPosted: August 22nd, 2017, 9:12 pm 
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Joined: March 2nd, 2013, 2:43 pm
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Location: Potomac, MD
My guess is that the cc LED lamp circuit is overly sensitive to the noise introduced onto the line. Since I build switchers, I have seen all kinds of weird stuff happen. Just ask Tom about my 2.5-amp fuse blow outs with having less than 0.6 amps load current.

Good filters are expensive and require physically larger parts than companies like Apple want to put in, and it may be consumer acceptance as much as cost.

David


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