Many electronic devices require a stable supply of electricity for normal operation. The electric network, generators and chemical batteries alone cannot provide this condition. Therefore, modern electronics is equipped with power supplies in which voltage and current stabilizers are present.
Voltage regulator
Under Art. voltage (U) understand the device, the circuitry of which is assembled in such a way that in automatic mode allows you to keep the level (U) at the consumer input unchanged within the specified limits. Applied devices in cases where the power source does not have stable electricity.
Depending on the type of electricity, devices are:
- alternating voltage;
- constant voltage.
According to the principle of action:
- compensation type;
- parametric.
With these devices it is impossible to achieve perfect alignment, but only partially mitigate destabilization.
Current stabilizer
Current stabilizers (I) are also called current generators. Their main task is to issue a constantly stable current (I) regardless of what load is connected at the output of the device (meaning load resistance). To ensure this condition, without exception, all devices have an input impedance of large values.
The scope of the devices is extensive. They are used in the power supply circuits of LED lamps, discharge lamps and always in chargers, where the option of changing the value of the charging current is used.
As the simplest scheme of Art. advocates a combination - a voltage source plus a resistor. This is a traditional LED power circuit. The disadvantage of this technical solution is the need to use a high (U) power source. Only this condition allows the use of a high-resistance resistor to achieve a stabilization effect.
Types of stabilizers
When considering voltage and current stabilizers, you need to understand that they are of different types for all kinds of electricity. So, the classification divides them into devices for working in DC or AC circuits. According to the principle of stabilization, there are compensation and parametric schemes.
In devices of the parametric type, radio elements are used in which the current-voltage characteristic (CVC) has a non-linear form. So, these elements for working with alternating voltage are chokes with a saturated ferromagnetic core. The issue of stabilization of constant voltage is solved at the expense of stabilizers and zener diodes. The current is stabilized using transistors - field workers and bipolar.
The voltage and current stabilizers of the compensation type work on the principle of compensation when comparing the actual parameter of electricity with the reference given by a specific unit of the device. In such systems, there is feedback through which a control signal arrives at the control element. Under the influence of the signal, the parameters of the controlled device change in proportion to the change in the input electricity, and at the output it remains stable. Compensation devices are continuous regulation, pulse and continuous-pulse.
Both parametric and compensation voltage and current stabilizers can be characterized by mass, quality and energy indicators. Qualitative for stabilizers (U) include:
- input voltage stabilization coefficient;
- internal resistance of the circuit;
- ripple equalization coefficient.
For stabilizers (I):
- coefficient of the input (U) current stabilization;
- coefficient of stabilization in the process when the load changes;
- coefficient of art. temperature.
The parameters of an energy nature include:
- Efficiency
- the power that the regulating element is able to dissipate.
Adjustable voltage and current regulator
To obtain stabilization with the ability to control electrical parameters and a higher coefficient, complex transistor circuits are used.
The scheme consists of:
- Art. current on the transistor VT1. Its task is to issue a direct current to the collector, which then goes through the amplifier and to the base of the regulating element.
- Amplifier (I) on VTy bipolar. This transistor responds to a voltage drop across a resistive divider.
- Regulating element on the transistor VT2. Thanks to it, the output (U) either decreases or increases.
To power household appliances, AC voltage stabilizers are used. Standard parameters of such devices:
- The ability to adjust (U) the output without distorting the signal.
- Stabilization of a large voltage spread at the input from 140 to 260 volts.
- High rate of accuracy of maintenance (U) with a discrepancy of not more than 2%.
- High efficiency.
- Availability of overload protection circuits.
Schemes of current and voltage stabilizers
Parametric device (U) assembled according to a single-stage scheme.
The scheme consists of:
- The zener diode, on which one voltage value drops, regardless of (I) passing through it.
- A quenching resistor where surplus (U) is released with increasing current.
- A diode acting as a temperature compensator.
According to the two-stage scheme.
Such schemes have the best stabilization indicators, as they consist of:
- The preliminary stabilization stage, performed on two series-connected zener diodes, where there is also thermal compensation due to the positive and negative temperature coefficients of the radioelements.
- The stabilization terminal stage is on a zener diode and a quenching resistor, which is powered by the first stage.
The parametric current device in the field according to the scheme - the source-gate are shorted.
Since there is no (U) between the source and the gate of the field effect transistor, it passes only a certain value (I) regardless of changes in the input voltage. The drawback of the circuit is related to the scatter of the characteristics of field workers, which makes it difficult to establish the exact value of the stabilized current.
Parametric voltage stabilizer with built-in current stabilizer.
The circuit is a combination of a single-stage voltage stabilizer, where instead of a quenching resistance, a stabilization element (I) on the field pole is included. This design has a larger stabilization coefficient.
Compensating stabilizer with (U) constant value and continuous control.
DIY electricity stabilization device
Modern stabilizing devices are implemented in microcircuits. You can assemble a voltage and current stabilizer with your own hands using the LM317. This is the simplest setup that does not require adjustment.
Instead of a printed circuit board, you can use a plate of getinaks or textolite. It is not necessary to etch the tracks. The circuit is simple, so it is more convenient to make contacts with wire segments.
Conclusion
It is important to know that all the regulatory elements in the circuits can get very hot, especially for microcircuits. Therefore, they must be installed on the radiator.
For reliable protection of household equipment among industrial design devices, the Resanta AC voltage stabilizer can be used.