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 Post subject: Do LED bulbs have power supplies in them?
PostPosted: Nov Sat 16, 2019 3:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Louisiana
Do the screw-in LED bulbs have power supplies in them, like the compact florescent bulbs do?


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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Sat 16, 2019 3:47 am 
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Joined: Mar Sun 01, 2009 10:27 pm
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Location: Ann Arbor, MI
They nave power supplies in them, but they are much simpler than what is in the compact florescent bulbs.
For a LED bulb all you have to do is drive the LEDs with a regulated constant current. Now for dim-able bulbs things get more complicated.

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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Sat 16, 2019 1:23 pm 
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Location: Arlington, VA USA
Tom Schulz wrote:
Now for dim-able bulbs things get more complicated.


And even more so with Philips WarmGlow. These start out at 2700k and change to 2200k the more they are dimmed. I have these in my living room and they are awesome! The perfect replacement for incandescents.

https://youtu.be/Pb_oKB7CrJI


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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Sat 16, 2019 3:05 pm 
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I always considered the "oranging" of incandescents at low voltage to be a fault vs virtue.

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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Sat 16, 2019 5:15 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: dayton oh usa
yes.
and this is one case where the cheap ones produce the least rfi.
simple capacitor ballast.
rfi from cfl and led bulbs has been a problem in the past for me.
buy a new type and take them right back to the store.
yes they work but they jam radio reception.
manager cant understand why this is a defect.
if the stores get enough returns for rfi maybe the mfrs will get the hint.
i tore apart a bunch of the offenders and found no rfi suppression parts at all in most.


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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Mon 18, 2019 2:32 am 
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Joined: Feb Sat 22, 2014 1:40 am
Posts: 241
If you are really interested, Bigclivedotcom has tear downs of LED bulbs.
Clive has hundreds of videos just tearing things apart so you don't have too!
He has a least a hundred on different LED lights, look through or do a search on his video page.
Ok, I did the LED search on his page, found over 500 LED tear downs! WOW!!
Search through those, there are several AC line powered LED bulbs.
https://www.youtube.com/user/bigclivedo ... LED+lights

Mikek


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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Mon 18, 2019 5:27 pm 
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Joined: Dec Sat 24, 2011 9:17 pm
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Location: Vancouver Island, Canada
I have an LED bulb in a reading lamp. It goes dark when shut off, then gradually develops a faint glow.
Unplug lamp cord, bulb goes dark, stays dark.

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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Mon 18, 2019 6:06 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 10097
Location: Santa Rosa, CA
Is it on a dimmer or timer switch external to the lamp?

Solid state switches (triacs) have measurable leakage current, so the trickle of current may be enough for a dim glow. If the switch is completely mechanical, a complete open circuit is created; likewise pulling the plug does the same.
I had a similar problem with "blinking" CFL and LED lamps that were on a timer wall switch. A small leakage current was slowly charging the filter cap in the lamp causing a "relaxation" oscillation and blinking. Changing to a mechanical timer solver the problem.

Rich


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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Tue 19, 2019 2:45 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 837
Location: dayton oh usa
the lighted switches with the neon bulb in the handle can cause this blink or glow issue too.
i put a 100k resistor in a fixture here to stop the annoying blink on a circuit with a lighted switch.
allowed the switch to light but not charge the cap in the led bulb.


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 Post subject: Re: Do LED bulbs have power supplies in them?
PostPosted: Nov Tue 19, 2019 4:50 pm 
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Joined: Dec Sat 24, 2011 9:17 pm
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Location: Vancouver Island, Canada
Just a simple chain pull switch on a table lamp plugged into a wall outlet.
The bulb glow is only visible in the dark.

I tried reversing the polarized plug, using an old adapter. No difference. With the switch off, something is causing the bulb to be slightly energized, but there is no voltage measurable with my DMM at the empty socket. Either socket, same result.
Pull the plug out of the wall outlet, glow is cut off.
The LED bulb is a leakage detector.


Attachments:
LED bulb.jpg
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Burl Ives, RIP, oldtimer.
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