LED backlighting can work both on batteries and on batteries. Their full discharge will not happen if you accidentally forget to close the compartment, as the backlight is endowed with a simple circuit with a timer. And the light will automatically go out after about 15 seconds.
Here's what it looks like:
We will need:
- Three-pin reed switch.
- Round magnet or any other shape.
- Transistor IRF840, you can take a similar other.
- 500 ohm resistor.
- 300 ohm resistor (optional).
- Resistor 20 Ohm (to reduce the current of LED strip - you can not put).
- Capacitor 22 uF.
- 25 cm LED strip at 12 V. The size of the tape is naturally at your discretion.
- 8 pieces of batteries of type - "AA" or "AAA".
- 1 meter wire.
Simple backlight circuit with timer
The circuit is very simple. In fact, the simplest time relay is assembled on the transistor. The load of the transistor is a piece of LED strip.
Or so, who will understand:
How does magnetic reed contact
Everything is very simple. I bring a magnet to it and the middle contact rises to the upper contact. Letting go - everything returns to its original position.
Build backlight with timer
Solder the resistor to the transistor.
Solder the rest of the circuit details.
Solder the wires to the LED strip and connect to the timer.
Assembling a battery of batteries
We twist into thick paper. Solder wires to the outputs. With force we fix everything with tape.
Check the timer
We measure the time of work. If everything suits - order!
Glue the LED strip in the right place. Nearby we fasten the whole circuit with batteries.
Install the magnet on the drawer.
Everything works without problems. I would like to add that you do not need to underestimate the batteries - they will last for at least 2 years, moreover, with the most active use. Of course, I would not recommend using batteries, since they have a large self-discharge.
Watch the video tutorial
You can see more detailed information on the video.