Thanks, Tim. Any chance I can fry the lights?
Chuck Norcutt
Tim Hughes wrote:
> I would guess the Leds have a Cheap 1N4004 diode connected in series
> with them, so they aren't damaged by the possible large reverse
> voltage, or they may be connected in pairs back to back so one LED
> conducts on one half of cycle and the other on the other half cycle.
> They must also include a current limit of some sort, probably just a
> small resistor potted into the connector. In theory a triac dimmer
> should work over part of its range if the string uses with a current
> limit resistor, but it may be the current draw (probably ~20mA) is so
> low the dimmer circuit itself will not function properly.
>
> If it were me I would just try it.
>
> You could also try connecting a small incandescent light in parallel
> with the light string, to increase the load a bit for the dimmer to
> operate on.
>
> tim Hughes
>
>
> --- On Mon, 12/15/08, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
> wrote:
>
>> From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> Subject: Re:
>> [OM] [OT] LED Christmas lights and an incandescent dimmer??? To:
>> "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx> Date:
>> Monday, December 15, 2008, 7:54 PM Thanks, but I think I'll just go
>> buy an inline switch. :-)
>>
>> Chuck Norcutt
>>
>> WayneS wrote:
>>> Then I don't see why a dimmer should not work. The
>> string probably
>>> has enough in series to drop 120VAC, and the natural
>> diode
>>> action means they only use 1/2 of the cycle. the
>> diodes must have
>>> good reverse voltage breakdown. Peak voltage is 163V.
>> divide by two and
>>> you get 80 bulbs in series.
>>>
>>> The dimmer effect may be a bit non-linear, but should
>> work.
>>> Wayne.
>>>
>>> At 07:24 PM 12/15/2008, you wrote:
>>>> These LEDs connect directly to the 120v supply.
>> There is no visible
>>>> converter. The plugs are even normal size for an
>> incandescent string of
>>>> lights so I don't think there's anything
>> hiding in there except a fuse.
>>>> They look exactly like a normal string of small
>> incandescent bulbs
>>>> except that they're LEDs. The bulbs also pop
>> in and out of sockets like
>>>> they would if they were small incandescent bulbs.
>> Bulbs are stated to
>>>> be 2 volts and 0.04 watts. A box of them consists
>> of either 2 strings
>>>> of 90 bulbs or 3 strings of 60 bulbs for 180 bulbs
>> drawing only 7.2 watts.
>>>> Chuck Norcutt
>>>>
>>>> WayneS wrote:
>>>>> LEDs are DC so there must be an AC to DC
>> converter. Without knowing
>>>>> the details of that converter it may, or may
>> not work.
>>>>> Wayne
>>>>>
>>>>> At 04:56 PM 12/15/2008, Chuck wrote:
>>>>>> What happens if I plug my LED Christmas
>> tree lights (120v) into an
>>>>>> incandescent dimmer switch? ...
>>>
>>>
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