Home Guy wrote in news: snipped-for-privacy@Guy.com:
no,whatever is dropping the **170V** peak-rectified line V to 3.5V is what's consuming the extra power.You have to consider the TOTAL V-drops for power consumed.
170 x .025 = 4.25W.
A "white" LED is just a blue LED with phosphors on top of the die,the blue LED(also emits UV) energizes the phosphors to give off a "white" light. that's why they appear yellow when off. That's the phosphors you see.
that's why both blue and "white" LEDs have the same V-drop;around 3.5V.
That would be true if the "whatever" were purely resistive. But this is "more complex...". Capacitive reactance is involved. That causes a phase shift between the voltage and current (voltage lags behind current) which lowers the instantaneous power.
Not claiming you should have bought LED versions back then just mentioning that I saw poor results with the devices you mentioned. And come to think of it they are gone from the various other places I have seen them being used.
Yours seems to be a lot like that light bulb in the NYC firehouse that has been burning for the last 89 years (or whatever).
Thanks, I would have no use for it other than to see your circuit and notes. If you spent some time on it and it's real pretty I'd love to have a look. Please include the word "Usenet" in the subject line, as I have a filter to only let them through. Thanks!
In the blue LED nitelite that I have, it is a 0.33 uf capacitor..... The LED had a diode across it in the other direction to keep the cap from charging up on the half cycle. A couple of resistors for inrush limiting and cap leakage... That's it...
Here's a page showing a few circuits for powering one or two LED's directly from 120 Vac power line.
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Plus lots of other LED circuits that remind me when I was building stuff like this on a breadboard back in junior high.
But yes, it seems common to use a capacitor and resistor in series, as well as as diode across the LED:
========== Using a capacitor to drop the voltage and a small resistor to limit the inrush current. Since the capacitor must pass current in both directions, a small diode is connected in parallel with the LED to provide a path for the negative half cycle and also to limit the reverse voltage across the LED. A second LED with the polarity reversed may be subsituted for the diode, or a tri-color LED could be used which would appear orange with alternating current.
The circuit is fairly efficient and draws only about a half watt from the line. The resistor value (1K / half watt) was chosen to limit the worst case inrush current to about 150 mA which will drop to less than
30 mA in a millisecond as the capacitor charges. This appears be a safe value, I have switched the circuit on and off many times without damage to the LED.
The 0.47 uF capacitor has a reactance of 5600 ohms at 60 cycles so the LED current is about 20 mA half wave, or 10 mA average. A larger capacitor will increase the current and a smaller one will reduce it. The capacitor must be a non-polarized type with a voltage rating of 200 volts or more. ===========
Arrgh- accidently clicked the wrong 'reply to' line- thought I finally had the hang of this new version of Tbird.
IMHO, the further you get from white light, the better. In addition to night vision issues, white light, especially if it is close to the parts of the daylight spectrum humans can see, kicks off the 'it's morning- get up' algorithm in the brain. When I get the middle-of-the-night hydraulic pressure alarms, I avoid turning on any white lights, and find it MUCH easier to get back to sleep. Between all the equipment LEDs and digital clocks scattered around the house, and ancient orange neon night lights in each bath, the only thing I have to watch out for is the refrigerator light, if I need a swig of something for cotton mouth, or to wash down a sinus pill. (the OTHER thing that often wakes me up at night.) I shut my eyes and avert my head, and find the jug in the door mainly by feel.
What I am interested in is... What's the company name of the dollar store where you got them? Is it "Dollar Store" or some other cheap price store like 'Family Dollar Store', 'Dollar Tree', 'Dollar General', or some other name?
Note: D2 is used to simulate the LED, D1 is in parallel with D2 but facing opposite.
This is a nodelist for a PSPICE simulation, and presented this way so other simulators can be used...
The voltages/currents are done with a transient simulation and steps of .01 ms for 50 ms....... Forget the first cycle.... takes that long to stabilize.
Result: D2 has a half wave peak current of about 20 ma.... The phase between V1 and the current out of V1 is greater than 80 degrees.. You=92ll have to look closely....
Andy replies: In Corsicana, Texas , it is called "Dollar Tree"... We also have Family Dollar, where things now cost $1.50 USD and Dollar Store, where things cost $2.00 USD...
Dollar Tree is my favorite. No prices are marked. Everything there is a dollar unless it is on sale, and marked down..... I wish they sold beer..... :>(((((
Andy in Eureka, Texas .... P.E.
Eureka, where the telephone lines have more clicks and chirps than a Ubangi wedding ceremony...
Des, I'm pretty sure that Han's wife made him put the light in so he could have better aim at night, and not wake her up by turning on the bathroom light......
LEDs built into kitchen and bathroom faucets are way cooler than lighted toilet seats:
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======== Another innovative design of kitchen faucet that has illuminated LED lighting. This mood lighting is come from nozzle head through the water flow. The LED has manual light switch. Contemporary convenience from the combined water and lighting that will give your bathroom an interesting looks. This faucet with LED is one of Franke Rolux kitchen product. This design is available in steel chrome and also black. Pull out the faucet head and the light goes where you need it, along with the water flows a pot or hosing the place down after dinner. ========
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