Lamp oscillator for atomic frequency standards

An apparatus for providing excitation of a vapor discharge lamp, comprising:

• a regulated DC power source;
• an oscillator circuit coupled to said power source, and including a first transistor configured with regenerative feedback, said first transistor having an excitation output coupled to said vapor discharge lamp;
• control means for controlling said oscillator circuit, said control means including a control op-amp having a first input coupled to a reference voltage, a second input coupled to said output of said first transistor, and an output coupled to an input of said first transistor;
• and
• a shift circuit having an input coupled to said output of said first transistor and having an output coupled to said output of said control op-amp, wherein said shift circuit samples the r.f. signal generated at said output of said first transistor and rectifies said r.f. signal to generate a DC shift signal corresponding to said r.f. signal having a polarity opposite to the polarity of the output of said control op-amp, said DC shift signal thereby shifting the operating range of said control op-amp in a direction opposite to the polarity of said DC shift signal.

An apparatus for providing excitation of a vapor discharge lamp, comprising:

• a DC power source with a regulated substantially constant output voltage;
• an oscillator circuit coupled to said power source output voltage, and including a first transistor configured with regenerative feedback, said first transistor having an excitation output coupled to said vapor discharge lamp;
• first circuit means for controlling said oscillator circuit to establish and maintain a substantially constant DC voltage at said output of said first transistor, said first circuit means including a control op-amp having a first input coupled to a reference voltage, a second input coupled to said output of said first transistor, and an output coupled to an input of said first transistor, and wherein a shift circuit samples the r.f. signal generated at said output of said first transistor and rectifies said r.f. signal to generate a DC shift signal corresponding to said r.f. signal having a polarity opposite to the polarity of the output of said control op-amp to force said control op-amp to generate an output voltage to nullify a voltage of said DC shift signal, thereby shifting the operating range of said control op-amp;
• and
• second circuit means for controlling a current flow through said first transistor, wherein during an ignition stage of said vapor discharge lamp said second circuit means establishes a current flow through said first transistor at a first current level sufficient to ignite said vapor discharge lamp, and after ignition of said vapor discharge lamp, said second circuit means reduces said current flow through said first transistor from said first current level to a second current level.

An apparatus for exciting a vapor discharge lamp, comprising:

• a DC source providing a substantially constant voltage;
• an oscillator circuit connected to said substantially constant voltage, including a current sensing resistance and providing an output for exciting said vapor discharge lamp;
• an oscillator control circuit connected with said current sensing resistance and adapted to control said oscillator circuit to maintain a substantially constant DC voltage across said current sensing resistance;
• and
• switching means responsive to light from said vapor discharge lamp for reducing the resistance of said current sensing resistance;
• and
• whereby said output for exciting said vapor discharge lamp provides an increased current for igniting the vapor discharge lamp and a reduced current when said vapor discharge lamp is ignited and a substantially constant voltage swing capability under both conditions.