Night Vision Enhancer green LED-based flashlights are widely used by hunters and other similar activists to light up their way and to alert other hunters of their presence. Greenlight does not interfere with the hunt, as animals are blind or indifferent to green light. Green is also a good night-vision retention color that allows one to distinguish colors such as yellow and red on maps and charts.

In the Night Vision Enhancer kit component of this flashlight is a 555 timer that is configured as an Astable multivibrator generating a 50 percent duty cycle square wave at approximately 6Hz frequency. Three green LEDs are connected at output pin 3 of 555 Timer. Switch S1 is the main on/off switch. In normal mode, LM555 IC is disabled by normally-closed (N/C) push-to-off switch S1 keeping its output low.

As a result, all LEDs (D1, D2, and D3) glow continuously with this Green Light Kit. On the other hand, when S2 is depressed, LM555 timer IC is enabled and all LEDs start flashing. You can also use this flashlight as a signal lamp. Flashing frequency can be varied by changing the value of the capacitor.