GE LED Nightlight

Saaby · #1 06-17-2003, 10:16 PM

I picked up a GE GELCore Etched Art Night Light at Wal-Mart today for just over $4. I opened it up to take the Etched Art out in hopes it would brighten it up. Inside is a rediculously simple circut, 2 big resistors and a diode. Can I add more LEDs or what?

I searched around the board but couldn't find anything [img]/ubbthreads/images/graemlins/frown.gif[/img]

Darell · #2 06-17-2003, 10:29 PM

Hey Apple Boy -

Feel free to add a few LEDs in series. I typically *at least* pop them open and replace the stock, cheapie LED for a better one. Yeah, the circuit is simple and HUGE. Some of them have a fuse, others do not.

snuffy · #3 06-17-2003, 10:32 PM

Post deleted by snuffy

Saaby · #4 06-17-2003, 10:51 PM

What it has going for it, though, is I don't have to assemble it.

I have no less than 3 LED Night Light Circuts laying around here waiting for assembly...ah, but it's summer now...

Darell · #5 06-17-2003, 11:17 PM

A couple of them are from me, right? It is worth it to make some neat tiny ones. Save the little boards for tiny projects that you can't build any other way. Use the big ugly circuits for your "standard" (ugly)projects.

Saaby · #6 06-17-2003, 11:19 PM

Yup. 2 from you. I'm going to do something cool with them...just haven't decited what yet [img]/ubbthreads/images/graemlins/wink.gif[/img]

Saaby · #7 06-27-2003, 01:53 PM

Who wants to splain how this circut works??

It's AC, so obviously + and - switch 60 times a second...but anyway

+>Diode>Resistor>Resistor>LED>-

So my limited understanding of electronics wonders...why 2 diodes?!?

Chris M. · #8 06-27-2003, 02:43 PM

By 2 diodes you mean the LED and the other diode? Easy.

LEDs have a low reverse voltage and current tolerance. More than the forward voltage hence why you don`t cook them that easilly if you get a battery in upside down (not true for Luxeon LEDs of course!). It`s around 5 volts for a bog standard 5mm red`un, not sure about whites but it`s probably similar if not less. During the positive half of the AC cycle the LED will allow forward current to flow, which gets limited by the resistors to a sensible level. When that AC cycle flips negative, the LED`s the wrong way up and hardly any current is flowing, asides the reverse leakage. That voltage will get right up to the peak of, I forget, something like 170v. Almost all that will be right accross the poor LED since negligable current is flowing, hence hardly any voltage gets dropped accross the resistors. Leave it there long enough and the poor diode will die from excessive reverse current.

As it is at 60Hz, the periods of reverse voltage are short, but frequent too - half the time! The LED may not let out the magic smoke right away but it won`t live like that for long. So, introducing the other diode. That one has a high reverse voltage tolerance which will withstand the full negative AC potential and let none of it to the LED. Result? LED lives a long and decent life.

[img]/ubbthreads/images/graemlins/grin.gif[/img]

Saaby · #9 06-27-2003, 02:44 PM

Ahhh! Ok, I knew LEDs had poor reverse voltage tollerence and (Doh!) I thought this was true of ALL diodes. Then again, if it was, what would be the point [img]/ubbthreads/images/graemlins/grin.gif[/img]

Saaby · #10 06-27-2003, 03:45 PM

Ah..ok I put 3 3mm 20 degree LEDs in that Don sent me a million years ago. It's AWESOME! I need to epoxy it. Pics later.

McGizmo · #11 06-27-2003, 09:05 PM

waiting....................... :d

shankus · #12 06-28-2003, 08:34 PM

I am wondering why there are two resistors in there. To get the right value of resistance or wattage? Are they in series or parallel?

PsycoBob[Q2] · #13 07-10-2003, 07:50 PM

I'm going to guess that it's to spread the wattage out, as they have to live with around 10mA of current, but they account for a big voltage drop.

I'm guessing that the average current through the LED is about 10mA, with peaks as high as 30mA for the 170v peak mentioned above. Roughly 60v average voltage, given that power flows half the time, 5700ohm resistors (0.57w) for 10mA average, and 29.29mA peak @ 170v.

Even that 0.57 the resistors have to get rid of can be pretty noteworthy, and power-resistors seem to be rated with the assumption that they'll have free-air movement to cool them, and enough spaceto avoid having the hot resistor melt a plastic.

dat2zip · #14 07-11-2003, 12:15 AM

Take a look at the light when it's plugged in. Fix your eyes and move your head back and forth. Does the light flicker? If so, it's only 30Hz. The way it has been drawn, diode - resistor - resistor - LED is a classic short cut cost savings measure. It is only running on 1/2 cycles and thus has noticeable flicker.

The two resistors are there to spread the heat since one resistor probably can't take all the power. I'm probably guessing that they have tweeked it for maximum brightness and I wouldn't be surprised to see 20mA RMS or so into the LED.

Darell · #15 07-11-2003, 12:44 AM

Yeah, but what does Wayne really know about this kind of stuff? :bigwink:

[img]/ubbthreads/images/graemlins/grin.gif[/img]

Tomas · #16 07-15-2003, 12:58 AM

Uh, Wayne, if it's running on just the positive or the negative half of the cycle it is still running at 60Hz - 60 half-cycles on and 60 half cycle off during each second.

dat2zip · #17 07-15-2003, 02:12 AM

Full wave rectification is 120HZ. So, yeah, you are correct and you don't see 120Hz as bad. 1/2 Cycle or 60Hz creates more flicker than 120Hz full wave rectfication.

Most eyes are annoyed or can perceive 60Hz.

Wayne

Saaby · #18 09-24-2003, 06:00 PM

Well guys I'm a slow young fart. After months and months I finally remembered to buy epoxy so the light is sitting on the table all gooped up drying now. It's not the greatest epoxy job ever but hey! It's my first time...cut me a break.

Only problem is there are 2 holes in the top where I epoxied. They're not that large, but they are large enough to allow the epoxy to flow down into the light--so when I was done I had epoxy slowly flowing out the vents in the bottom of the light [img]/ubbthreads/images/graemlins/eek.gif[/img] you think it's still safe to operate this thing? I mean I didn't use thermal epoxy. I guess if the now mostly potted resistor heats up enough to start a fire or something it'll just poof inside the light and it'll go out. I suppose having completely potted electronics makes this even safer for bathroom use?

BLU3_SHOCK · #19 01-27-2004, 02:44 PM

hey i brougt a guide light from wallmart about 2 weeks ago they were only 3 dollars when i put the thing in the wall outlet i was upset the thing was like a light house shape peice of plastic this thing was very weak it seemed to me like it only used a very cheap red 5 mm led. they also came in sailboats and stuff that and it is hard to open it because i already tryed to open it if you find a way to open the item that i am talking about then please post how you opened your thanks for your time this is just my 2 cents.

BLU3_SHOCK · #20 01-27-2004, 02:48 PM

all you have to do is chang the resisters values to fit the leds you want to run one question what color led would you want it to be i might be able to give you a hook up i just got some real bright leds.

gwbaltzell · #21 01-27-2004, 04:43 PM

[ QUOTE ]
BLU3_SHOCK said:
hey i brougt a guide light from wallmart about 2 weeks ago they were only 3 dollars when i put the thing in the wall outlet i was upset the thing was like a light house shape peice of plastic this thing was very weak it seemed to me like it only used a very cheap red 5 mm led. they also came in sailboats and stuff that and it is hard to open it because i already tryed to open it if you find a way to open the item that i am talking about then please post how you opened your thanks for your time this is just my 2 cents.

[/ QUOTE ]
"Guide lights" and "marker lights" are only intended to be bright enough to be seen themselves. Likely what you have is a neon bulb not a LED. The GE package will say LED somewhere and GELcore on the newer ones. This thread turned to a LED discussion and I posted pictures of the current and older GE models as well as a "neon colored LED" one from Dollar Tree.

George