Getting ~200ma out of AC for nightlight?

[Illum]

While we have a proliferation of new threads based on convering existing LED night lights I haven't been able to find one that winds up from incan

I "rescued" this nightlight from a garage sale at no cost after deciding off the bat that it would be a good LED candidate...little did I know its secrets.

The simplist form of an AC driven LED circuit is this


Granted the concept of this was initially designed for 5mm LEDs
D1 was a 5mm white
D2 was used with a 1N4003 diode
R1 was a 100Kohm, 1/2W resistor

If I was to underdrive a CREE at 150-200ma, what resistor value do I need? Or should I do away with this circuit and use something else?

I'm pretty sure the 1N4003 can survive:candle:

the nightlight in question is this [NNL-10, first one top left]


Penny on top


Split

In stock mode it houses two neon lamps each wired to a 3.3K ohm resistor and the output is ridiculously low. Orange at best and consumes about 0.25W each on AC

In addition to the near opaque cover a LuxI driven at 50ma can't even penetrate it [not to mention 5mms]. so I hooked up the power supply and tried 150ma with a CREE XR-E "Q4" and it looked very nice, all yellow and fancy.

The interior space is a decent cylinder 2-3/16" diameter at 3/8" deep, which should be partially filled by a 1/8" heatsink soon

I'm inclined to step down the AC through the use of 1N4004s in the same manner as several dynamo hub lights in the bicycle section, but I'm not sure what to do after that. Plus whatever compensation I have to include for AC drops and peaks:shrug:

Any idea where to start?

 

[blasterman]

Simple bridge circuit, isn't it?

No annoying flicker, or strobing when you wave your hand by it?

 

[LEDninja]

115 VAC RMS produces ~170 VDC peak.

170 V * 20 mA = 3.4 W for a typical LED nitelite.

With a 100000 ohm resistor:
A = 170 V/100000 ohm = 0.0017 A or 1.7 mA. Methinks OP's basic circuit would be very dim.
W = 170^2/100000 = 0.285 W so a 1/2 W resistor would work.

170 V * 200 mA = 34 W for a Cree. Too much heat. You will need some form of power supply/regulator instead of a simple dropping resistor.

 

[hank]

Hm, I'm surprised that isn't bright enough, we use that kind, with just one neon lamp, around our house. We mount it on the bottom side of a cube tap and use a bit of aluminum tape on the side to make it a purely _indirect_ light source, to get the floor lit enough for walking around without any risk, without seeing the thing directly. As a direct light source, it's bright enough to wipe out your ability to see anything more than a few feet away from it.

 

[Illum]

Hank, without the covers yes its quite bright...but who ever designed this particular model obviously hasn't seen the light, near half of the cover is opaque and the few places that arent are around 1/16" thick of non-transparent plastic...if they had made it at least see-through I would have thought better of it.

Currently all it is doing is providing an "indicator pilot lamp" of sorts to tell me the AC line is working properly. It illuminates little else compared to a 4W incandescent night light I have around


While the 20ma option sounds feasible, I was just curious as for the options available :thanks: