Using an LM317 voltage regulator and some electronic components can be made a very simple optical warning. Used in a device it can make a small 12 V bulb to flash . Output voltage is not stabilized by the circuit: it is only a few volts lower than the input voltage. Circuit current limiting done automatically at startup, so that greatly increases lamp reliability.
Using electronic circuit diagram below can be designed a device which turn on and off the light in several rooms in random order. This electronic circuit in same time with decreasing of ambient light will turn on light and leave it on for 1… 5 hours .
The circuit can be used to create the impression that there are staff in the building which is attached (useful when you are away on vacation) or to automatically turn on the light in different rooms.
An on off switch with a single button can be designed using electronic diagram below. Schmitt trigger output toggles N1 when the switch is closed briefly. This operation is achieved with a chassis that simple circuit because the input trigger threshold levels are maintained between tipping. If the trigger output is logic "1" logic, the capacitor C1 will charge through R1. When switch S1 is closed, the entry will be passed in the state trigger logic "1" and output will be "0" logic.