The SD-2 is a small electronic device that delivers substantial current to an incandescent infrared source: Up to 19 Amps peak and 2.8 Amps average.

Pulsable sources are turned on and off with a programmable, low frequency, 50% duty cycle square wave. The on portion of the square wave is a 10 kHz Pulse Width Modulated (PWM) drive signal. Steady state sources are pulsed continuously with the 10 kHz PWM signal. This results in very high thermal and electrical efficiency.

The SD-2 microprocessor controls the source based upon non-volatile,
internally stored values that can be modified via the RS-232 link.