Remote Living > Lighting

Fun investigating E27 LED lamps

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OperaHouse:
I've just been playing with some cheap 120V E27 9W LED lamps. A Philips for $2.50 easily runs at low power with a .05uF capacitor in series or a 70,000 ohm resistor. That is like a neon lamp! I have one in the basement operating at milliwatt power levels so the dog can see the steps at night. Looking with a scope it is a simple full wave bridge with a resistor in series and a smoothing cap. The current spike indicates a capacitor being charged. Turn on is at about 80V so these lamps could be used with a boost converter with that much DC voltage. I tried operating the lamp with a diode in series to create half wave rectification. This is not only a simple method for dimming but indicates a capacitor is not used in place of a dropping resistor.  Top trace is current and lower is voltage.  This lamp would start to illuminate at 60VDC.

Tried a capacitor in series with a $2 Zilotek in an identical looking package. That unit would repeatedly flash at about a half second rate. That would have been nice for Holoween. Obviously this has an electronic ballast that waits for a capacitor to charge up before the inverter starts.  I thought with an inverter circuitthe starting voltage might be a lot lower.  However, it would only start once it reached 90VDC and after that itneeded 75V to maintain an on condition.

A capacitor in series with a $3.50 FEIT 7.3W failed to light at all. That unit would not turn on till 115VDC was reached.  The transition to on was smoth and likely does not have any active electronics. It likely hasan anti ghosting resistor to prevent the lamp from lighting due to capacitive effects.  In another 3.5W spot the anti ghosting resistor consumed about a quarter watt. This lamp obviously has a LED string of over 100V.

I imagine that these LED lamps will suffer some of the same issues as the low cost CFL lamps. Both lamps with plastic bases have a 9-10 year rated life expectancy with three hours use a day. That indicates they know the LED is being over driven at a high temperature. The base of the lamps get quite hot and only has plastic to transfer heat.  The FEIT has a finned metal base and at least makes an effort to remove heat from the LED.  I don't remember the declared operating life on the packaging, but it seemed a lot longer like double that of the other two lamps.  In just this small sample of lamps it was interesting to see totally different design approaches.

OperaHouse:
I tried to attach a 53K JPF file to the first post for a couple days and it would not post because it said it was too large.  I just tried to do just the picture in another post and that failed.  Tried to post just a comment in another post and got this message.


There are attachments found, which you have attached before but not posted. These attachments are now attached to this post. If you do not want to include them in this post, you can remove them

hiker:
Your not alone....get the same message when I try to post a pict. Off of this dam I phone...perhaps it's time to allow bigger pict. Uploads....even with a 56k modem..it's really not that slow...ho hum.....😜

DamonHD:
Hi,

I think something has broken with the upload facility.  Please stay tuned to this frequency...

Rgds

Damon

SparWeb:
Same trouble here, with uploading pictures of any size/type.

Hopefully Damon can shed some light on OperaHouse's LED's.

::)

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