It is known that for the operation of any electrical appliance and electrical equipment, a voltage of a certain value is required, however, for powering different devices, this figure may differ. The process of lowering DC and AC voltage is an integral part of any electrical substations, electrical installations and the operation of household appliances, gadgets and appliances used in home conditions.
For example, according to PUE 6.1.16-18 the power supply of portable lamps should be no higher than 50 volts, for their bladeless use, but the standard voltage value used in many countries is 220 or 230 volts. For power supply of any electronic system assembled on microprocessor elements, it is about 5 Volts DC. In this regard, there are several ways to change, downward, the magnitude of the direct and alternating current.
Ways to reduce the magnitude of alternating voltage
Alternating voltage, both high-voltage (at substations above 1000 Volts) and low-voltage (220 and 380 Volts) used in the power supply of residential and non-residential premises can be reduced by two ways:
1. Transformer. A transformer is an electromagnetic device made of a core (magnetic circuit) and connected inductively winding, the purpose of which is to convert the magnitude of the alternating voltage without frequency changes. Moreover, it is capable of changing the value both in the direction of decreasing and increasing.
At the same time, the transformer method is one of the most common, simple and safe, since due to galvanic isolation, that is lack of direct electrical contact between the windings, the probability of the primary voltage being hit is reduced to a minimum side, in this case of a larger value, the device connected to the secondary (step-down winding of the transformer) is protected contactless communication.
It should be noted that there are so-called autotransformers that are able to change the voltage value at the terminals on the low side by rotating the knob.
2. The reduced AC voltage using a transformer can then be easily rectified using diode or diode assembly with a capacitor and a zener diode to improve the quality of the constant voltage.
3. Transformerless. This method is used in inexpensive power supplies, mainly made in China, and consists in changing the magnitude of the alternating voltage using a ballast capacitor. This method is used to power low-power electronics, such as LED lamps, flashlight batteries. The main disadvantage of transformerless ones is the high probability that the supply voltage (high) will hit the downside, as a result of the breakdown of the capacitor C1.
In any case, it is imperative to take into account not only the magnitude of the reduced voltage, but also the current strength of the secondary circuits, which is directly proportional to the power supplied by the electrical equipment.
Ways to lower DC voltage
In practice, situations do not often arise in which it is necessary to reduce the magnitude of the constant voltage. At the same time, it is very problematic to reduce it several times in a simple way, there are only simple methods for lowering the constant voltage by several volts, for example, from 12V to 9V, or it is often necessary reduction of 5 Volt power supply to 3V.
This can be done in several ways:
- By connecting several diodes in series. Each diode, depending on the characteristics, is characterized by a voltage drop, so their number will be selected depending on how much it is necessary to lower the potential;
- By changing the parameter of the resistor and zener diode in the circuit of the original power supply. However, without a schematic diagram and experience with electronics, this will be problematic.
There is another way to change the magnitude of the direct current to the required one, by converting the constant voltage into variable using an inverter circuit, and then its subsequent transformation and rectification, but this method is hardly a simple one perhaps.
I covered these and other methods in even more detail in my new video: