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120v LED bulbs -- innards

Started by mkr5000 December 21, 2011
I've actually googled the heck out of this several times but can't seem to get a definitive answer on what is REALLY going on inside a typical 120v LED bulb.

Is it --

** a capacitor to limit current and a power resistor plus a series stack of leds? (and 60hz flicker isn't noticed?)

** a bridge rectifier (couldn't use a half wave could you?), plus the above? 

** or just the rectifier and resistor (no cap)

or?

does anyone know?

I would imagine the same scheme is used with pretty much all manufacturers. Certainly there aren't sophisticated drivers in a lamp (maybe just some higher priced ones?)

thanks for any answers.
I am interested in this myself. I think it is some sort of a
transformer-less
power supply, to keep down cost and weight. A cap would be needed
though to control steady state current. Let us see what the gurus say.

On Dec 21, 9:33=A0am, mkr5000 <miker...@gmail.com> wrote:
> I've actually googled the heck out of this several times but can't seem t=
o get a definitive answer on what is REALLY going on inside a typical 120v = LED bulb.
> > Is it -- > > ** a capacitor to limit current and a power resistor plus a series stack =
of leds? (and 60hz flicker isn't noticed?)
> > ** a bridge rectifier (couldn't use a half wave could you?), plus the abo=
ve?
> > ** or just the rectifier and resistor (no cap) > > or? > > does anyone know? > > I would imagine the same scheme is used with pretty much all manufacturer=
s. Certainly there aren't sophisticated drivers in a lamp (maybe just some = higher priced ones?)
> > thanks for any answers.
try to search google images  for: circuit LED bulb

bye
delo


On Dec 21, 8:43=A0am, Daku <dakup...@gmail.com> wrote:
> I am interested in this myself. I think it is some sort of a > transformer-less > power supply, to keep down cost and weight. A cap would be needed > though to control steady state current. Let us see what the gurus say. > > On Dec 21, 9:33=A0am, mkr5000 <miker...@gmail.com> wrote: > > > > > > > > > I've actually googled the heck out of this several times but can't seem=
to get a definitive answer on what is REALLY going on inside a typical 120= v LED bulb.
> > > Is it -- > > > ** a capacitor to limit current and a power resistor plus a series stac=
k of leds? (and 60hz flicker isn't noticed?)
> > > ** a bridge rectifier (couldn't use a half wave could you?), plus the a=
bove?
> > > ** or just the rectifier and resistor (no cap) > > > or? > > > does anyone know? > > > I would imagine the same scheme is used with pretty much all manufactur=
ers. Certainly there aren't sophisticated drivers in a lamp (maybe just som= e higher priced ones?)
> > > thanks for any answers.
It probably depends on the manufacturer. The one I got has a transformer and rectifier. Look like a full regulator.
On 22/12/2011 12:33 AM, mkr5000 wrote:
> I've actually googled the heck out of this several times but can't seem to get a definitive answer on what is REALLY going on inside a typical 120v LED bulb. > > Is it -- > > ** a capacitor to limit current and a power resistor plus a series stack of leds? (and 60hz flicker isn't noticed?) > > ** a bridge rectifier (couldn't use a half wave could you?), plus the above? > > ** or just the rectifier and resistor (no cap) > > or? > > does anyone know? > > I would imagine the same scheme is used with pretty much all manufacturers. Certainly there aren't sophisticated drivers in a lamp (maybe just some higher priced ones?) > > thanks for any answers.
This one: http://www.dealextreme.com/p/b22-4-5w-7000k-360-lumen-30-x-5050-smd-led-white-light-bulb-220v-73096 is a 1uF polyester cap (not mains rated BTW), tiny bridge rectifier, 30 diodes in series and nothing else. -- We have failed to address the fundamental truth that endless growth is impossible in a finite world.
On Dec 21, 9:37=A0am, David Eather <eat...@tpg.com.au> wrote:
> On 22/12/2011 12:33 AM, mkr5000 wrote: > > > > > > > > > > > I've actually googled the heck out of this several times but can't seem=
to get a definitive answer on what is REALLY going on inside a typical 120= v LED bulb.
> > > Is it -- > > > ** a capacitor to limit current and a power resistor plus a series stac=
k of leds? (and 60hz flicker isn't noticed?)
> > > ** a bridge rectifier (couldn't use a half wave could you?), plus the a=
bove?
> > > ** or just the rectifier and resistor (no cap) > > > or? > > > does anyone know? > > > I would imagine the same scheme is used with pretty much all manufactur=
ers. Certainly there aren't sophisticated drivers in a lamp (maybe just som= e higher priced ones?)
> > > thanks for any answers. > > This one: > > http://www.dealextreme.com/p/b22-4-5w-7000k-360-lumen-30-x-5050-smd-l... > > is a 1uF polyester cap (not mains rated BTW), tiny bridge rectifier, 30 > diodes in series and nothing else. >
If 1 out of 30 failed, ...
I should have mentioned also -- the LED bulbs that are trying to replace conventional medium base bulbs I'm particularly interested in. Popular LED replacements for standard 40w, 60w etc.
On Dec 21, 10:17=A0am, mkr5000 <miker...@gmail.com> wrote:
> I should have mentioned also -- the LED bulbs that are trying to replace =
conventional medium base bulbs I'm particularly interested in. Popular LED = replacements for standard 40w, 60w etc. Mine look like this: http://www.alibaba.com/product-free/110162425/LED_Bulb/showimage.html It's 120V/240V auto detect, just like most laptop adapters.
On 22/12/2011 4:17 AM, mkr5000 wrote:
> I should have mentioned also -- the LED bulbs that are trying to replace conventional medium base bulbs I'm particularly interested in. Popular LED replacements for standard 40w, 60w etc.
B22 is the light bulb standard - at least in OZ. You only asked what they have inside which is pretty irrelevant to what kind of base it has. This one would easily replace a 40W and perhaps even a 60W. I think the white of the light fools the brain into thinking it is much brighter - in any case it is easy to read under. I think it also comes in ES and if not there is an adapter. -- We have failed to address the fundamental truth that endless growth is impossible in a finite world.
On Thu, 22 Dec 2011 03:37:14 +1000, David Eather <eather@tpg.com.au>
wrote:

>On 22/12/2011 12:33 AM, mkr5000 wrote: >> I've actually googled the heck out of this several times but can't seem to get a definitive answer on what is REALLY going on inside a typical 120v LED bulb. >> >> Is it -- >> >> ** a capacitor to limit current and a power resistor plus a series stack of leds? (and 60hz flicker isn't noticed?) >> >> ** a bridge rectifier (couldn't use a half wave could you?), plus the above? >> >> ** or just the rectifier and resistor (no cap) >> >> or? >> >> does anyone know? >> >> I would imagine the same scheme is used with pretty much all manufacturers. Certainly there aren't sophisticated drivers in a lamp (maybe just some higher priced ones?) >> >> thanks for any answers. > >This one: > >http://www.dealextreme.com/p/b22-4-5w-7000k-360-lumen-30-x-5050-smd-led-white-light-bulb-220v-73096 > >is a 1uF polyester cap (not mains rated BTW), tiny bridge rectifier, 30 >diodes in series and nothing else.
It's better to have a resistor in series too, so that line spikes don't push a huge amount of current into the LEDs. John