Patent ID: 8717168

Claim:
An alarm unit, comprising: a flash circuit having a flashtube for generating a flash; an application specific integrated circuit (ASIC) coupled to the flash circuit, for triggering the flash, wherein the ASIC controls an energy level of the flashtube via a sense resistor in a current sensing circuit coupled to the ASIC, wherein the ASIC operates a charge cycle for the flashtube at a constant frequency selected from a range above 8 kilohertz (kHz) to 16 kilohertz; a switch, coupled to said ASIC and disposed within a housing of the alarm unit, wherein said switch is tamper resistant after the alarm unit is installed while still allowing a selected intensity setting to be visible, where said switch has a plurality of selectable positions representative of a plurality of intensity settings, wherein said flash has an intensity that is in accordance with a selected position of said switch; and a voltage doubler to provide the plurality of intensity settings, wherein the voltage doubler provides a voltage across the flashtube based upon one of the plurality of intensity settings.