Voltage indication means for an electronic flashing device

In an electronic flashing device having

• a flashing discharge tube;
• a main discharging capacitor for firing said discharge tube by means of energy stored in said discharging capacitor;
• and
• a DC-DC converter including a transistor coupled to a D.C. power supply, a transformer having primary, secondary and auxiliary windings coupled to said D.C. power supply and said transistor to form an oscillatory circuit, a sub-capacitor coupled between the auxiliary winding of said transformer and said transistor, a rectifier element interposed between the secondary winding of said transformer and said main discharging capacitor for rectifying the voltage generated across said secondary winding to allow charging of said main discharging capacitor, and a voltage dividing resistor having a tap intermediate the ends thereof connected across the primary winding of said transformer;
• a voltage indication device for indicating when the voltage across said discharging capacitor has been charged to a predetermined charged value, comprising
• a switching device having a control electrode connected to the tap on said voltage dividing resistor, an anode and a cathode, and
• a light emitting indication device having a definite threshold voltage above which light is emitted connected in series with the anode-cathode circuit of said switching device, said series-connected light emitting indication device and switching device being coupled across the primary winding of said transformer, the tap on said voltage dividing resistor being set to render said switching device conductive when said discharging capacitor has been charged to said predetermined charged value.

In an electronic flashing device having

• a flashing discharge tube;
• a main discharging capacitor for firing said discharge tube by means of energy stored in said discharging capacitor;
• and
• a DC-DC converter including a transistor coupled to a D.C. power supply, a transformer having primary, secondary and auxiliary windings coupled to said D.C. power supply and said transistor to form an oscillatory circuit, a sub-capacitor coupled between the auxiliary winding of said transformer and said transistor, and a rectifier element interposed between the secondary winding of said transformer and said main discharging capacitor for rectifying the voltage generated across said secondary winding to allow charging of said main discharging capacitor;
• a voltage indication device for indicating when the voltage across said discharging capacitor has been charged to a predetermined charged value, comprising
• a switching device having a control electrode, an anode and a cathode,
• a light emitting indication device having a definite threshold voltage above which light is emitted connected in series with the anode-cathode circuit of said switching device, said series-connected light emitting indication device and switching device being coupled across said sub-capacitor, and
• gate voltage applying means connected to said sub-capacitor for applying a gate voltage to the control electrode of said switching device, said auxiliary winding having a number of turns N.sub.b given by the relation ##EQU9## where N.sub.2 designates the number of turns on said secondary winding, V.sub.D said definite threshold voltage and E.sub.2 ' the predetermined charged voltage of said main discharging capacitor.

In an electronic flashing device having

• a flashing discharge tube;
• a main discharging capacitor for firing said discharge tube by means of energy stored in said discharging capacitor;
• and
• a DC-DC converter including a transistor coupled to a D.C. power supply, a transformer having primary, secondary and auxiliary windings coupled to said D.C. power supply and said transistor to form an oscillatory circuit, a sub-capacitor coupled between the auxiliary winding of said transformer and said transistor, and a rectifier element interposed between the secondary winding of said transformer and said main discharging capacitor for rectifying the voltage generated across said secondary winding to allow charging of said main discharging capacitor;
• a voltage indication device for indicating when the voltage across said discharging capacitor has been charged to a predetermined charged value, comprising
• a switching device having a control electrode, an anode and a cathode,
• a light emitting indication device having a definite threshold voltage above which light is emitted connected in series with the anode-cathode circuit of said switching device, said semiconductive light emitting indicator device and switching device being coupled between one terminal of said D.C. power supply and the positively charged electrode of said sub-capacitor, and
• gate voltage supply means connected across the auxiliary winding of said transformer for applying a gate voltage to the control electrode of said switching device, and auxiliary winding having a number of turns N.sub.b given by the relation ##EQU10## where N.sub.2 designates the number of turns of said secondary winding, V.sub.D said definite threshold voltage and E.sub.2 ' the predetermined charged voltage of said main discharging capacitor.