Patent ID: 7737949

Claim:
A control circuit compromising: a first port for connecting an illumination device; a second port connecting said control circuit to a power supply; a drive circuit connected to said first port, said drive circuit passing a current between said first port and said second port having an amplitude determined by a control signal connected thereto; a potential measuring circuit that generates a signal indicative of a drive circuit potential between said first and second ports; and a controller that generates said control signal, wherein said controller records said drive circuit potential for a predetermined current when said first port is connected to an illumination device and said controller sets said control signal based on said recorded drive circuit potential, said controller being configured to set said control signal to provide a first drive current suitable for semiconductor lasers when said drive circuit potential indicates that said illumination device is a semiconductor laser, said controller being configured to set said control signal to provide a second drive current suitable for light-emitting diodes when said drive circuit potential indicates that said illumination device is a light-emitting diode, wherein said controller determines an impedance for said illumination device and compares that impedance to impedance values in a table stored in said controller, and wherein said impedance is determined by measuring said drive circuit potential when first and second currents are caused to flow through said illumination device.