For assembly, you need a minimum of parts and a minimum of funds.
LED, (2 possible), the cost of 15 rubles in auto the store. In the circuit on the LED, you need to change the current-limiting resistor, in the store it costs 12 volts, I have 3 volts without a resistor.
Transistor structure npn КТ 3102 or КТ 315 or similar foreign analogues.
The resistor, for tuning the variable, I set 330 K, (which was at hand), set the constant to 320 K.
Battery 3 Volts, (from PC or Laptop), 15 rubles in the store.
A container for the battery, (removed from the burned motherboard from the laptop).
The first option was made with a 9 volt relay. Tests showed the gluttony of the circuit; overnight, a Krona type battery sat down from 9 to 6 volts. True, it was not the first freshness from the multimeter.
According to the scheme:
I replaced the circuit with a simpler one, not hot in terms of power and compact, and a circuit with a relay is useful for a more serious toy, for example, so that the kettle itself turns on in the morning at dawn, get up, and the teapot has already boiled!
New scheme:
The result is such a compact device
According to this scheme, you can make the backlight in the cabinet, in the shelves for linen, etc.
I asked the child for an old toy, though she still does not know about it.
Disassembled a Chinese toy in a sweat
And mounted a super compact fixture in a former toy and a future lamp
He fixed the gadget with an adhesive gun in an almost lamp and placed it on a double-sided tape on the aquarium to remove it when you need to wash the aquarium or replace the battery.
It turned out compact, beautiful and cheap!