A voltage divider is generally composed of two resistors, where the total voltage U tot splits into two partial voltages. The basic form is the unloaded voltage divider.
voltage divider are used to operating points (voltage ratio) set of active components. For example, a transistor amplifier circuit. Only a small current flow is generated. Mainly be generated by a voltage divider voltage potentials that are lower than the total voltage.
Voltage divider circuit
- Unloaded Voltage Divider (two resistors in series)
- oaded Voltage Divider
Unloaded voltage divider
An unloaded voltage divider comprises two series-connected resistors R 1 and R 2.
The current and voltage distribution in the unloaded voltage dividers is identical to the series circuit.Here, the same formulas and rules.
Unloaded voltage divider calculatation
The following formulas are used to calculate the partial voltages (voltage divider rules). They apply only if both resistors by the same current flows, so there is an unloaded voltage divider. In this case, calculate the voltage across the three-part set.
Loaded voltage divider
A loaded voltage divider consists of a series circuit of resistors R 1 and R 2. In addition, one of the two resistors by a consumer, in this case the resistance R L load (load resistance). The circuit is a series connection to a mixed circuit of parallel connection (R 2 | | R L) and series (R 1+ ( R 2| | R L)).
Loaded voltage divider calculation
The following formula is used to calculate the parallel resistance in the loaded voltage divider.
If the voltage divider loaded with a resistance, shall be held in the circuit following changes:
* The total resistance of the circuit is small.
* As a result, increases the total current I tot .
* The voltage drop U 1 at the resistor R 1 increases.
* The supply voltage U 2 across resistor R 2 becomes smaller.
Variable loads can be powered by low voltage divider with a fairly stable voltage. However, a voltage divider should not be burdened by a very small resistance. This leads to changes in the current and voltage distribution within the circuit. Thus, the voltage divider is useless.