| 摘要 |
1299523 Discharge lamp circuits BERKEY PHOTO Inc 24 Feb 1970 [21 April 1969] 8697/70 Heading H2H A circuit for operating a gas discharge lamp V1 comprises a triac SR1 connected in series with the lamp across an A.C. source the impedance of which forms the sole ballast, a control circuit for switching on the triac at a variable phase angle and a circuit for initially igniting the lamp at a variable phase angle corresponding to the variable phase angle at which the triac is switched. To initially ignite the lamp, a switch S1 is temporarily closed thereby charging a capacitor C2 via a resistance R7 and the source. After a time determined by the setting of a ganged resistor R8 a triac SR2 is triggered so that the capacitor C2 discharges and supplies a high voltage pulse to a transformer T1 to start the lamp. The triac SR1 is simultanously triggered and maintains the lamp on as it is switched on in each half cycle of the source voltage. The triac SR1 may be replaced by a pair of controlled rectifiers. |
