120 VAC to 12 VDC circuit to fit in E27 Base

[WLuna]

I want to start making my own LED lighting but need to find a small footprint, hopefully pre-made circuit that fits within a E27 Base Cap. I have just searched (almost) everywhere and have decided to just ASK. It needs to be about the size of the tip of a mans thumb to fit in the E27.

 

[berkeman]

I want to start making my own LED lighting but need to find a small footprint, hopefully pre-made circuit that fits within a E27 Base Cap. I have just searched (almost) everywhere and have decided to just ASK. It needs to be about the size of the tip of a mans thumb to fit in the E27.

I haven't seen that made yet, but it might exist. I googled E27 +"dc-dc" and got a few hits -- here's a semi-relevant hit:

http://www.globalsources.com/gsol/I/DC-DC-converters/a/9000000112276.htm

It discusses small form factor, and is associated with LED lighting to some extent, but it doesn't say there are already-existing versions to fit the E27 socket.

You can start off using the small switching 2-prong wall adapters (some are quite small now), plus a 2-prong socket adapter for the E27 socket (they fit flush in the socket). That's not as small as you want, but would let you start experimenting.

 

[mdjensen22]

Not sure if either of these will work for you:
http://www.powerint.com/sites/default/files/PDFFiles/rdr131.pdf
http://www.powerint.com/sites/default/files/PDFFiles/der261.pdfPower requirements go a long way...

 

[berkeman]

Not sure if either of these will work for you:
http://www.powerint.com/sites/default/files/PDFFiles/rdr131.pdf
http://www.powerint.com/sites/default/files/PDFFiles/der261.pdf


Power requirements go a long way...

ON Semiconductor also has similar Reference Designs, if you want to go the full-custom route on the design.

 

[mdjensen22]

Pretty much any SMPS manufacturer has similar reference designs to fit in the sockets (ON, PI, Fairchild, ST, etc.).

Those are usually a solid starting point for and typically you can buy the reference designs either through distribution or through their corporate sales. It makes it easy to buy one and start tweaking as needed.

 

[WLuna]

Thank you to all that have replied. I am amazed that there isn't a solution to my need already being mass marketed. I wish I had the resources and knowledge to get one to market. I know there are many people that would make their own LED light if that small feature was available. But I'm not done yet. Gotta keep looking..

 

[MATLABdude]

Thank you to all that have replied. I am amazed that there isn't a solution to my need already being mass marketed. I wish I had the resources and knowledge to get one to market. I know there are many people that would make their own LED light if that small feature was available. But I'm not done yet. Gotta keep looking..

There are, however, they usually come with LEDs pre-attached!

 

[WLuna]

Could I use a full wave rectifier to drive the LED's? Could I get it down to 12V and still have it fit in the E27?

 

[mdjensen22]

Could I use a full wave rectifier to drive the LED's? Could I get it down to 12V and still have it fit in the E27?

I doubt it would fit - the capacitor you would need would be pretty big or the resistor would be pretty descent sized and generate a lot of heat (assuming a transformerless supply).

http://ww1.microchip.com/downloads/en/AppNotes/00954A.pdf"If you could go higher than 12V, you could probably make one that would fit with a transformerless design but I wouldn't recommend that (not isolated & not efficient).
My guess is that a simple switch-mode power supply is the way to go. The layout will have to be done to get it to fit into the socket, but this is doable.

You could always get one of this type of light (See MATLABdude's post) and take it apart to see how it was done. This would at least tell you what voltage the LED strings are run off and what power supply topology was used. While you most likely will not be able to copy the design, it should point you in the right direction.

 

[WLuna]

Unfortunately, I [purchased a Boatload of 12V LED's for a project design for automobiles. So, I've got a couple thousand 12V LED's. But you do have a good point about just getting different LED's. Perhaps I should reverse engineer this project of mine. Find the power source then match the LED's to fit. So, let's drop the 12 VDC, So, New Suggestions are welcomed...

 

[mdjensen22]

Can't you just put a bunch of the LEDs in series which would allow you to up the voltage?
This will keep your power requirements to a minimum.

 

[WLuna]

The problem with Series, is if one dies, they're all out. And with the mold I'm planning, I won't be able to go back and replace them. Well, not easily.

 

[mdjensen22]

that's why you use multiple strings...

 

[WLuna]

Well MD... I strung 5 LED's with a 1/4 watt Resistor and just plugged it into the wall. I expected them to light then die, or at least one die. but they didn't. I'm sure they're flickering at 60 hz as well, but I can't see it. They lit and stayed lit for hours until I unplugged them. So, your suggestion was good. Now these are 12 vdc rated 5mm leds. Should I expect them to last the 100,000 hours they're supposedly rated to survive? Or how long should I expect? Since this experiment worked, I ordered 100 10mm 13000 mcd ultra bright and will try this again. How about the smd's? should I expect the same results from them as well? I would like to get into the much, much higher MCD ratings. But fear they would not last long enough for it to be worth it.

On another issue, although I can make some E27 base sockets (male) myself, I would prefer not to. Does anyone have a source I can acquire those from? Once I get the standard E27 formats working will, I plan to expand to the other socket sizes as well.