12V Malibu Deck Lighting

lambda

Flashlight Enthusiast
Joined
Jan 6, 2002
Messages
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Location
Iowa
I have Malibu deck lights (7 watt bulbs) installed as celling lights around my house and deck. The bulbs got so hot they melted thru the plastic light housing and were scorching the wood behind. This is a low voltage 12V AC system, UL approved (not what they used to be).

To fix this, I used 3 LEDs per lamp (with rectifier inline) I was able to replace the super hot bulbs with home made circuit cards and LEDs.

Now I've got that "moonlight" color with lights that equal what I had without the heat; everyone asks "what kind of lights are those?".

Just another practical use for LEDs.

Anyone else got 12V lighting system they haven't inspected since installation?

Got real good insurance?
 
Did you just use a rectifier in series with the bulbs? What value did you use? Also do you notice any flicker?
 
Yes, rectifier and three LEDs all in series; LEDs draw 37ma. Don't know what value or number, just had some surplus stuff laying around - at less than 40ma, I would think any diode/rectifier that could take 12VAC would do. Yes, there is a very slight kind of flicker if you look at the bulb, but not noticeable in the light it throws.
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by lambda:
Yes, rectifier and three LEDs all in series; LEDs draw 37ma. Don't know what value or number, just had some surplus stuff laying around - at less than 40ma, I would think any diode/rectifier that could take 12VAC would do. Yes, there is a very slight kind of flicker if you look at the bulb, but not noticeable in the light it throws.<HR></BLOCKQUOTE>
You may be able to correct some of the flicker by using capacitors in conjunction with the rectifiers, but if the flicker is that slight to begin with it's probably not worth spending too much time or money on...
 
That's a good idea about the capacitor.
Any guess about what microfarad size would work?

Thanks
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by JoeyL:
That's a good idea about the capacitor.
Any guess about what microfarad size would work?

Thanks
<HR></BLOCKQUOTE>

Dunno
I'd get the highest uF rating you could reasonably find for the voltage you are using, within monetary reason. Or maybe there's a scientific method to it all that I don't understand...
 
Actually, I tried a 100uf 35V cap and it pretty much flattens out the ripple. But the light actually looks better with the flicker. Hard to explain; yes, if you stare at the light (painful) there is some very fast slight flicker, but you don't notice it in the light it cast. Seems brighter without the cap; probably due to higher pulse current producing more light than the steady DC with the cap.
 
That is very interesting.

I just was playing with adding a large cap on my night light and I too noticed the light was dimmer. I thought is was me till I sat down and read this.

I can not explain why it appears brighter. But, to get rid of the flicker, try making a full bridge using 4 diodes or a diode bridge part. It will give you full rectification and I think that will also increase your brightness.
cool.gif
 
It's possible that the resistance in the capacitor has something to do with it, or perhaps the voltage it puts out during the discharge is too high or too low. There are some formulas at Illinois Capacitor that help you determine the power loss, the voltage during charge and discharge, et cetera, that could account for the difference in brightness when the capacitor is put in place. Maybe the voltage of the capacitor is too high for the application, and doesn't charge properly...
 
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