220 volts from a 3.7 V battery

In everyday life, we most often come across power supplies that reduce the high voltage in the network to a few volts, which are necessary to connect various devices. However, the reverse transformation can also be done. Moreover, the scheme is completely simple.
It can be useful in two cases:

• In order to connect equipment and devices that are powered by only 220 volts in the field.
  
• During power outages.

Well, don’t forget that experimenting is always fun. For example, I assembled this design simply out of interest, without an eye to practical application.
However, it should be noted that the presented converter is of low power and will not withstand a large load, for example a TV. However, as will be seen in the example, an energy-saving light bulb works from it.

Converter manufacturing

We only need a few details:

• Transformer from an old phone charger.
  
• Transistor 882P or its domestic analogs KT815, KT817.
  
• Diode IN5398, an analogue of KD226, or any other diode designed for reverse current up to 10 volts of medium or high power.
  
• Resistor (resistance) 1 kOhm.
  
• Small breadboard.

Naturally, you will also need a soldering iron with solder and flux, wire cutters, wires and a multimeter (tester). You can, of course, make a printed circuit board, but for a circuit consisting of several parts, you should not waste time on developing the layout of the tracks, drawing them and etching foil PCB or getinax. Checking the transformer. Old charger board.

A transformer soldered out of it.

Next we need to check the transformer and find the terminals of its windings. Let's take it multimeter, switch it to ohmmeter mode. We check all the conclusions one by one, find those that “ring” in pairs and write down their resistance.
1. First 0.7 Ohm.

2. Second 1.3 Ohm.

3. Third 6.2 Ohm.

The winding with the greatest resistance was the primary winding, 220 V was supplied to it. In our device it will be the secondary, that is, the output. The rest were relieved of the reduced voltage. For us, they will serve as the primary (the one with a resistance of 0.7 ohms) and part of the generator (with a resistance of 1.3). The measurement results for different transformers may differ; you need to focus on their relationship to each other.

Device diagram

As you can see, it is the simplest. For convenience, we have marked the winding resistances. A transformer cannot convert direct current. Therefore, a generator is assembled on a transistor and one of its windings. It supplies a pulsating voltage from the input (battery) to the primary winding, a voltage of about 220 volts is removed from the secondary.

Assembling the converter

We take a breadboard.

We install the transformer on it. We choose a 1 kilo-ohm resistor. We insert it into the holes on the board, next to the transformer. We bend the leads of the resistor so as to connect them to the corresponding contacts of the transformer. We solder it.It is convenient to secure the board in some kind of clamp, as in the photo, so that the problem of a missing “third hand” does not arise. Soldered resistor. We bite off the excess length of the output. Board with bitten resistor leads. Next we take the transistor. We install it on the board on the other side of the transformer, as in the screenshot (I selected the location of the parts so that it would be more convenient to connect them according to the circuit diagram). We bend the terminals of the transistor. We solder them. Installed transistor. Let's take a diode. We install it on the board parallel to the transistor. Solder it. Our scheme is ready.


Solder the wires to connect constant voltage (DC input). And wires for picking up pulsating high voltage (AC output).

For convenience, we take 220 volt wires with “crocodiles”.

Our device is ready.

Testing the converter

In order to supply voltage, select a 3-4 volt battery. Although you can use any other power source.

Solder the low voltage input wires to it, observing the polarity. We measure the voltage at the output of our device. It turns out 215 volts.

Attention. It is not advisable to touch parts while the power is connected. This is not so dangerous if you do not have health problems, especially with the heart (although two hundred volts, the current is weak), but it can “pinch” unpleasantly.
We complete the testing by connecting a 220-volt energy-saving fluorescent lamp. Thanks to the "crocodiles" this is easy to do without a soldering iron. As you can see, the lamp is on.

Our device is ready.
Advice. You can increase the power of the converter by installing a transistor on the radiator.
True, the battery capacity will not last long.If you are going to use the converter constantly, then choose a higher-capacity battery and make a case for it.

Watch the video