CONSTANT ELECTRIC POWER IN AN ILLUMINATION CIRCUIT

摘要

A power supply circuit for generating a power pulse train for an incandescent bulb in a flashlight which results in a relatively constant illumination output from the flashlight despite the decline in output voltage from a battery power supply therefor during discharge. The power supply circuit operates to compensate for the lower output voltage from the battery power supply by increasing the duty cycle of the pulse train to provide wider pulse widths therein, and eventually the wider pulse widths merge into a DC power supply near the end of the useful service life of the battery power supply.