It's no secret that halogen lamps are used in cars, often overlook out of action. This occurs as a result of inrush current, inevitably arisen once turned on, when the spiral filament is still cold (cold) state.
For example, "halogen" fog lamps are designed to work in normal mode with the consumption of a 55-watt power (12 volt supply). In according to known to every schoolboy-pupil act for an electrical circuit, the resistance of the filament should be about 2.6 Ohms. And in fact it is, but only when heated filament. The cold lamp the resistance measured by the ohmmeter, a little more than 0.2 Ohms. This means that in the moment you turn this "Halogens" it is inevitable to take place 60-ampere inrush current!
To extend the life of incandescent bulbs in the low voltage network and 's meant my proposed device.
The time for a smooth warm-up output lamp working temperature - dependent resistance of the resistor 141 and capacity capacitor C1. When specified on the diagram the values it does not exceed 2.5 s.
The saturation voltage of the composite transistor VT1-VТ2 you can install regulation of the rotor resistor R2. It allows to choose the desired time release mode (depending on load power) in the interval from zero to the maximum delay.
The choice CTA as power semiconductor triode is not accidental. This transistor NPO "Transistor" (Minsk) capable of withstanding for a long period of time, a large inrush current at I to 10 A. For optimal performance in our scheme it needs to be installed along with CTB on a common heat sink area of about 100 cm2, when the current consumed by the lamp, up to 6 A.
If the switch SА1 replace bridge and in series with the resistor R1 enable microtuber or microcopy an additional convenience - the lack of a power switch. His role now will be to perform the power transistor.
Due to the small size of the parts used in this unit, printed there is no fee. The entire Assembly is hinged manner (safe and well familiar with each school's laboratory works on physics).
Author: A. Filipovic