Patent ID: 6762652
Filing Date: 2004-07-13
Classification: H02M,Y02B

Abstract:
An oscillator for use in a preconditioner receiving an input voltage and delivering an output voltage, comprising:a timing capacitor with a first terminal connected to ground, and a second terminal connected to a switching element via a discharge resistance, the switching element being arranged to connect flue discharge resistance to ground when an output signal of the oscillator is LOW, thereby causing discharge of the capacitor with a discharge current equal to Idischarge=UCtR5,where R5 is the discharge resistance and UCt is the voltage of the capacitor,a transistor with an emitter connected to the input voltage via a resistance, a diode with an anode connected to the collector of the transistor and a cathode connected to the second terminal of the timing capacitor, and a first zener diode with a cathode connected to the base of the transistor and an anode connected to ground, so that, when the input voltage exceeds a zener voltage of the zener diode, a current flows through the transistor, reducing the discharge current to Idischarge=UCtR5-Ui&it;â€ƒ&it;n-Uz1R1+R2,where UIn is the input voltage, uz1 is the zener voltage, and R1+R2 is the resistance connecting the transistor to the input voltage.