voltage dividers are widely used in electronics because they allow an optimal way to solve problems of voltage regulation.There are various schematic solutions from the simplest, such as some wall lights, to a sufficiently complex as to shift control boards windings normalizers mains.
What is a voltage divider?Formulation simple - is a device that, depending on the transmission rate (adjustable separately) controls the output voltage relative to the input.
Earlier in the stores often you can find a lamp, wall lamp, designed for two lamps.Its peculiarity is that the lamps themselves have been designed to operate with a voltage of 127 volts.The entire system is connected to a household power socket with 220 and it worked successfully.No miracles!The thing is that the method of connecting conductors formed nothing else, as a voltage divider.Let us remember the basics of electrical engineering, namely, parallel and serial connection of consumers.As you know, the process of sequential switching current is equal and the voltage changes (remember Ohm's law).Therefore, in the example with a lamp bulb of the same type are connected in series, which allows the reduction of the supply voltage in half (110).Also, a voltage divider can be found in the device distributes signals from one antenna on several TVs.In fact, many examples.
Let's look at a simple voltage divider on the basis of two resistors R1 and R2.Resistance in series, to free the findings supplied input voltage U. From the midpoint of the conductor connecting resistors have an additional output.That is, there are three end: two - is external terminals (between the full value of the voltage U), and the average forming U1 and U2.
The calculation of the voltage divider, using Ohm's law.Since I = U / R, U is the product of current and resistance.Accordingly, the section to be voltage U1 R1, R2 and to be U2.The current is then equal to (series connection).Given the law for the full circuit, we see that the supply is the sum of U U1 + U2.
What is the current under these conditions?Generalizing the equation, we get:
I = U / (R1 + R2).
this we can determine the value of the voltage (U exit) at the output of the divider (it can be as U1, and U2):
exit U = U * R2 / (R1 + R2).
dividers adjustable resistance on a number of important features that should be considered at both the calculations and the operation.
First of all, such decisions can not be used to adjust the voltage of powerful consumers.For example, such a method can not be powered motor.One reason - this denomination resistors themselves.Resistance per kilowatt if they exist, are massive devices, scattering an impressive part of the energy as heat.
resistance value of the connected load should not be less than the electrical resistance of the divider circuit, otherwise the whole system will need to recalculate.Ideally the difference divider R and R of the load should be as large as possible.It is important to precisely match the values of R1 and R2, as the inflated ratings entail excessive voltage drop, and will be understated cool, wasting energy on heating.
calculating divider generally adjusted value of its current time (e.g., 10) is greater than the connected load amperage.Further, knowing the current and voltage is calculated total resistance (R1 + R2).Next, pick the tables nearest the standard values of R1 and R2 (given their allowable power to avoid over-heating).
