# HOW TO EXTEND THE LIFE OF THE BULB?

If you are tired to constantly change the bulb, use one of the tips below. But in all cases success is achieved through a substantial reduction in voltage. In the daytime and especially at night, the voltage often reaches 230-240 V, which leads to accelerated burnout of the filaments of light bulbs. It is estimated that the excess voltage of only 4% compared to the nominal (i.e., from 220 to 228) shortens the lifespan of the bulbs by 40% and with increased “power” of 6%, this period is reduced by more than half.

At the same time reducing the voltage on the lamps only 8% (200-202) increases the “experience” of their work in 3.5 times; with the 195 In it increases by almost 5 times.

Of course, with the voltage and decreases the brightness, but in many cases, particularly in offices and in public areas, this fact is not so important.

How to reduce the stress on the bulbs? There are two most simple way. The first — series two lamps (Fig. 1). And what kind of lamp to take the extra? Can be the same as the main. But then both lamps will Shine weakly. It is best to pick a few to power the lamps differed by 1.5—2 times, for example 40 and 75 watts, 60 and 100 watts, etc. Then the lower power lamp will glow bright enough, and more powerful is weaker, acting as a kind of ballast, absorbing excess voltage (Fig. 2).
At first glance, is not winning — it is necessary to use two lamps instead of one. But that shows a simple calculation. The voltage drop across the lamps in a series connection is distributed inversely proportional to their power. Therefore, when the voltage is 220 V (will take a couple of lamps 40 and 75 watts) 40 watt lamp the voltage will be about 145, and at its 75-watt “partner” — slightly more than 75 V. as the durability depends on the voltage level, it is clear that change will have mainly a lamp of lower power. And that, as practice shows, in the worst cases is at least a year. Under normal conditions, during this time, you have to change from 5 to 8 lamps (referring to the daily work within 12 hours). As you can see, the savings is quite noticeable.

Fig. 1. The scheme of serial connection of light bulbs.

Fig. 2. Extra lamps.

Fig. 3. Circuit of the diode.

The other way is sequential activation of the lamp and a semiconductor diode. Due to its small size it can be installed in the housing of the switch between the terminal and one of the lead wires. In this embodiment is a barely noticeable flickering of the lamps (due to half-wave rectification of the AC), and the average value of voltage on them is about 155 V.

Now select the type of diode. It needs to have some in stock at the applicable current and be rated for a voltage below 400 V. Of miniature diodes meet this requirement a series of КД105 and КД209. However, the diodes of the brand КД105 should be used with lamps that have a capacity not exceeding 40 W and the diodes КД209 (with any letter index) — collaboration with a 75-watt lighting fixtures. Of course, you can use more powerful diodes of other types, but then they have to install the outside switch. A properly selected diode is practically unlimited.

But what if your house is a total switch on all access? In this case, install a diode in high power. It is attached to a metal area, screwed with screws to the wall near the switch and case with ventilation holes.
Recommended diode types: КД202М, N, R or C, КД203, Д232— Д234, Д246—Д248 with any alphabetic index.

When choosing the type of diode, remember that the maximum permissible operating current (indicated in the passport of a semiconductor device) by 20-25% to exceed the total current drawn by all the lamps related to this switch. For example, if the diode allows current to 5 A, the total current of all lamps (it is easy to calculate by dividing the total wattage of all lamps with a voltage of 220 V) must not exceed 4 A.

And the last one. By connecting an additional lamp or diode, do not forget that you are dealing with high voltage, dangerous for your life. Therefore, be sure to power off the line and then get to work.

Yu ROSENBERG Ulyanovsk