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## Re: Diode in series with light bulb

 Subject: Re: Diode in series with light bulb "Ralph Mowery" Tue, 20 Dec 2005 18:02:05 GMT sci.electronics.basics
 ```"steve" wrote in message news:1135101130.732259.280690@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx > I was reading a web site that has information about light bulbs. Here > is a quote relating to a question I wanted to ask. > > -- Quote --- > "Reducing the voltage applied to a light bulb will reduce the filament > temperature, resulting in a dramatic increase in life expectancy. > One device sold to do this is an ordinary silicon diode built into a > cap that is made to stick to the base of a light bulb. A diode lets > current through in only one direction, causing the bulb to get power > only 50 percent of the time if it is operated on AC. This effectively > reduces the applied voltage by about 30 percent. (Reducing the voltage > to its original value times the square root of .5 results in the same > power consumption as applying full voltage half the time.) The life > expectancy is increased very dramatically. However, the power > consumption is reduced by about 40 percent (not 50 since the cooler > filament has less resistance) and light output is reduced by reduced by > about 70 percent (cooler filaments are less efficient at radiating > visible light)." > > --- > My question is really just a just wondering kind of question. I have no > interest in doing this. > > I have seen the type of "Savings " devices written about above. Would > the same thing be achieved if I simply took a diode of the proper > rating and put it in line in one of the wires running to an > incandescent light bulb? > Yes, you would get the same effect. Unless the bulb is in a hard to reach place you would be beter off just reducing the wattage of the bulb. The calculations I have seen (not verified) say you will save more on electricity than the extra bulb replacements will cost. ```
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