Gradual switching cct. for light sources - has phase control for switching triac and RC element whose capacito voltage supplies triac control electrode

摘要

The electronic switch gradually turns on a triac switch so that the lamp current rises slowly from zero to its maximum and thereby avoids the high initial currents that shorten the lamp service life. The triac is in series with the lamp and its gate is coupled over a firing circuit to the turn-on capacitor. To slow down the turn-on, a diode bridge is connected across the capacitor and its other diagonal contains an RC timing element. The RC element consists of a capacitor bridged by a resistor and coupled in series with another resistor. This RC element may also contain field-effect transistor.