LED power supply from 1.5 volt battery

LEDs have long replaced incandescent light bulbs from almost all areas. It's understandable: Light-emitting diode It is brighter than lamps, considering its energy consumption.
But there is also LEDs a number of shortcomings. Of course, we won’t talk about all of them, but we will discuss one. This is a high initial power threshold - it is about 1.8-2.2 volts. Naturally, you can’t power it from one battery...
To overcome this shortcoming, we will build a simple converter using an absolute minimum of parts.
Thanks to this converter you can connect Light-emitting diode (or several LEDs) to one battery and make a small flashlight.
We will need:

• Light-emitting diode.
  
• 2N3904 or BC547 silicon transistor, or any other n-p-n structure.
  
• Wire.
  
• Resistor 1 kOhm.
  
• Ring cores or ferrite cores.

Converter circuit

I will give you two diagrams. One for winding a ring transformer, the other for those who do not have a ring core on hand.


This is the simplest blocking generator, with a free excitation frequency. The idea is as old as time.The device will have a high efficiency.

Winding the inductor

Regardless of whether you use a ring core or a regular ferrite core, wind 10 turns of each winding. Your inductor is ready for this.

Generator check

We assemble according to the diagram and check. The generator should work and does not need adjustment.
If suddenly, even though the elements are working properly, the LED does not light up, try changing the ends of one of the windings of the induction transformer.
Now the LED shines very brightly even with a dead battery. The lower limit of the power supply for the entire device is now somewhere around 0.6 volts.
The efficiency of a transformer with a ring core is slightly higher. Not critical of course, but just keep it in mind.