dimming LED lights

Thread Starter

sky jumper

Joined Jun 14, 2013
2
newbie here.

I bought some new outside LED lighting fixtures for the garage and front door. they are too bright and annoy the neighbors. they consist of 3 LEDs in series running off a 10V 700ma supply.

to dim them I put a 2.2k resistor in series. now they flicker.

I then put a 33uF cap in parallel. flicker is reduced, but still flickers.

I also tried to disconnect 1 or 2 of them. the remaining ones flickered.

is there a quick way to dim these without having to build a fancy PWM controller??

and, could someone explain to me why they flicker? I'm an EE but have long forgotten the basics of LED circuit design.
 

#12

Joined Nov 30, 2010
18,224
How about a piece of colored plastic for a lens? It's not an electrical idea at all, but if you're resourceful and lucky, you might get a good result.
 

Thread Starter

sky jumper

Joined Jun 14, 2013
2
I'm not sure about the specifics of the power supply. it says 6-10V DC output, 700ma. it's part of the fixture, so I'd assume it was designed specifically for this application.

I may try the colored lens idea -- i thought of that but couldn't readily find a suitable plastic lens that would fit. I have tons of resistors...

I could try to open the power supply. it appears to be a sealed unit. but if I could open it, how would I know how to alter the design parameters without schematics?
 

GopherT

Joined Nov 23, 2012
8,009
Get a piece of white polycarbonate from the home improvement store. If they don't have white, get clear and wipe acetone (fingernail polish remover) on it until it is fairly opaque. Make sure you remove the protective film from the poly sheet befor treating with acetone (it will be obvious if protective film is present).

You can also go to the thrift store and buy a glass dome from an old light fixture and break it to a size that fits over your LEDs.

To stop the flicker, you may need a much larger capacitor (3300 to 6800 uF) if you go that route. You may not have space for that.
 

#12

Joined Nov 30, 2010
18,224
Now it is the next day and I thought about the "blinkers" that go on horses. Flat plates that narrow the beam so it doesn't shine on the neighbors. Another idea is to cut slots in a piece of sheet metal to direct the light and misdirect some of it so it doesn't get out of the fixture.
 
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