Monday, February 14, 2011

LED Torch Uses Blocking Oscillator


This simple LED torch is driven by a 2-transistor blocking oscillator which steps up the voltage from a 1.5V cell. It relies on the inherent current limiting of the 150µH choke to protect the white LED from over-drive. With a 9V zener diode in place of the white LED, it could also provide a 9V supply provided the current drain is modest.
Circuit diagram:

LED torch uses blocking oscillator circuit schematic

Author: Peter Goodwin
Copyright: Silicon Chip Electronics

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