Here, ultra simple circuit of an obstacle indicator is presented. Just assemble the circuit on a piece of general-purpose circuit board and then enclose it in small ABS box. Next, attach the unit on the solar panel mast using suitable clamps. This little circuit takes power from the 12V battery of the solar system and switch on a blinking white light spot, when dc power supply from the solar panel is absent, ie at night time!

The solar power system guard circuit is a gated astable multivibrator wired around the”evergreen” tiny timer chip LM555(IC1). The thing that makes this design special is the ultra-low current consumption. The white clear glass type LED (D3) flashes only very briefly each time with a duty cycle near 10%. The circuit is gated through diode D1 such that the flashing only begins when sufficient supply from the solar panel is absent.