In the memorable 1990-e years I worked at the Kirov plant instrument maintenance computer. Every morning we had to go down to the basement to enable refrigeration. Bulbs in the basement then disappeared, burned out. In short, as a rule, to see the switch, had to use matches: even to buy a flashlight for the plant was the problem. Then appeared the idea to make such a lamp yourself. From the power supply batteries and battery items I refused: they often fail, leak or anything. I did almost “eternal” condenser flashlight.
As a source of energy is used the capacitor C1 of large capacity (150 000,0 мкФх16 In) produced by ELKO. The amount of energy a capacitor is 15 joules (j). Charging is via dneproprudnyi the rectifier VD (Teal КД105) from the AC charging voltage. At the same time it serves to protect from improper supply voltage. Charging of the capacitor is controlled by the HL1 light bulb (6.3 V, 0.3 A). Its gradual extinction means the end of the process.