If in the dark you repeatedly stumble across objects in your home before reaching the light switch, why not signal it to make it easier to locate? This simple circuit that can be embedded in any switch has extremely low power consumption (less than 0.01 W) and uses few low cost components.
When the switch is turned off, the warning light comes on, causing the small neon lamp to flash. In figure 1 we have the complete circuit of the flag. Capacitor C1 is a polyester with at least 100 V working voltage for any 110 V or 220 V network.
In figure 2 we show the installation of the circuit in a common wall switch.
Material list
D1-1N4004 (110V) or 1N4007 (220V) - Silicon Diode
R1 - 1 M ohms x 1/8 W - resistor - brown, black, green
C1- 220 nF x 100 V or more - polyester capacitor
NE-1 - Neon Bulb NE-2H or equivalent
Miscellaneous - wires, soldering, etc
