LED lighting can be powered either by batteries or rechargeable batteries. They will not be completely discharged if you accidentally forget to close the compartment, since the backlight is equipped with a simple circuit with a timer. And the light will go off automatically after about 15 seconds.
This is what it looks like:
Without backlight:
We will need:
- Three-pin reed switch.
- Round magnet or any other shape.
- Transistor IRF840, you can take a similar one.
- Resistor 500 Ohm.
- 300 Ohm resistor (optional).
- 20 Ohm resistor (to reduce the current of LED strips - you can omit them).
- Capacitor 22 uF.
- 25 cm LED strip for 12 V. The size of the strip is of course at your discretion.
- 8 pcs of “AA” or “AAA” type batteries.
- 1 meter of wire.
A simple backlight circuit with a timer
The scheme is very simple. In fact, a simple time relay is assembled on a transistor.The load of the transistor is a piece of LED strip.
Or this way, whoever understands it better:
How does the magnetic contact of a reed switch work?
Everything is very simple. I bring the magnet closer to it and the middle contact rises to the top contact. I let go - everything returns to its original position.
Backlight assembly with timer
Solder a resistor to the transistor.
Solder the remaining parts of the circuit.
Solder the wires to the LED strip and connect to the timer.
Assembling a battery from batteries
Roll it into thick paper. We solder wires to the outputs. We secure everything with tape.
Checking the timer operation
We measure the working time. If everything suits you, everything is fine!
Installing the backlight
We glue the LED strip to the required place. Nearby we attach the entire circuit with batteries.
Install the magnet on the drawer.
Result of work
Without backlight:
With backlight:
Everything works without problems. I would like to add that you should not underestimate batteries - they will last for at least 2 years, and even with the most active use. I would certainly not recommend using batteries, as they have a high self-discharge.
Watch video instructions
You can see more detailed information in the video.
