LED flashlight on one battery

Everyone wants their flashlight to last long and shine brightly. An excellent option with such qualities is an LED flashlight. Even better if it can run on just one battery. The LED requires at least 3.5 volts to work properly, so theoretically you need at least three batteries. Can an LED run on a single battery?
Certainly. Inventive and economical people came up with the idea of ​​using a choke to store energy.
A LED flashlight that runs on a single battery can even be made by hand! How to do it? Today we will tell you!

Our homemade flashlight will require:

  • LED (preferably very bright)
  • Small Variable Resistor
  • Ring transformer (which we will make ourselves)
  • Transistor type KT 315
  • Base (you can take a ready-made flashlight case)

We wind the inductor on a small ferrite ring (you can take it from the power supply of your computer). We wind two windings with a 0.4 mm wire, making 30 turns from the middle (15 in each direction). To get it right, both windings must be wound in the same direction. As a result, we will have four wires. Two of them, different in color, need to be connected to each other.
You can choose any transistor. The main thing is that it should be low-frequency, direct conduction.
We collect our device according to the scheme in a case and fix it in it.


Such a flashlight will be economical and bright at the same time. The converter will work even with a power supply of 0.6 - 2 volts. Although, of course, in order for the flashlight to work for a long time, it is better to take a good alkaline battery with a capacity of about 1.2 volts. But keep in mind that when using such a battery, you will need to make a socket to recharge it.

What did we get?

Even a hand-assembled LED flashlight will have a lot of advantages!

  • Brightness (depends on the LED you choose, but in any case it will burn brighter than a regular light bulb)
  • Durability (any LED is stronger than a light bulb, so the likelihood that it will stop working from a fall is negligible)
  • Economical (working on a single battery, our flashlight gives a bright good light)
  • Efficient (efficiency like any LED device will be about 90%)
  • It works for a long time (such a flashlight will serve for a very long time, regardless of how often you turn it off / on).

In conclusion, I would like to note the fact that LED flashlights currently occupy almost 95% of the market for low-volume lighting devices.

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