Priming circuit for low pressure fluorescent tube - compensates for mains fluctuations using thyristor control switching as function for electrode potential difference

摘要

A priming circuit for a low pressure gas discharge tube ensures reliable ignition even with fluctuations in the mains supply or tolerance deviation, of the tube. This helps to increase the effective life. The electrodes of the tube are heated by a current. They are connected in series with a choke and with a switching element which is in the non-conducting mode when the tube is ignited. The switching element (5) can be switched over from the conducting to the non-conducting mode as a function of the electrode voltage appertaining between the two electrodes (2) when the tube (1) is not ignited. The switching element is controlled by pulses drived from a controlled rectifier, shunted by a capacitor (9).