Abstract: The seeker of a guided missile may be tested by a simulator. The simulator mimics the reflection of a pulsed laser beam from a target. The simulator has a low power IR emitting LED 18. This IR emitting LED 18 is pulsed by an energy storing capacitor 22. The pulse is controlled by an SCR 16 driven by a pulse repetition oscillator 12. A collimating lens 26 collects light from the IR emitting LED 18 and directs it to the seeker. When being self tested, IR from the IR emitting LED 18 is reflected by a mirror 40 onto a detector 24. The output of the detector 24 is passed through a high pass filter 30. This removes signals from IR noise sources (fluorescent bulbs, the sun, incandescent bulbs), and passes only signals from the IR emitting LED 18. A first buffer 32, preferably an amplifier, provides power between the high pass filter 30 and the gate of a second SCR 34. This second SCR 34 drives a visible light LED 36 through a second buffer 38. The visible light LED 36 acts as a positive self test indication.