Demand for voltage stabilizing systems has grown significantly in recent years. Of particular interest is shown in devices working with artificial lighting sources and, in particular, with LEDs. The current stabilizer on the lm317 is a simple, inexpensive, but reliable device that you can purchase or assemble yourself. In the latter case, you need to know the basic rules of instrumentation, safety requirements when working with electricity and prepare a standard set of elements.
Why stabilization of current and voltage is necessary
The number of electrical devices in homes is constantly growing. In recent years, the number of electrical appliances has increased several times. As a result, the demand for voltage levels in electric networks has increased. Moreover, most of the buildings (residential and industrial) and power plants were built more than 30-40 years ago.
Some modern devices are made with built-in stabilizers - small circuits to prevent breakdowns from power surges. But most of them do not contain additional devices, and even a small difference in the network threatens to burn out. In the high-risk group, large household appliances (not digital). In particular, boilers and washing machines.
To avoid damage and ensure a stable voltage in the network, install stabilizers. In every home, this is optional. If the building has a constant current supply without serious changes (within 220 volts with a maximum error of 10%), there is no point in additional devices. But when the jumps are constant, the installation of a stabilizer will save technology and provide electricity.
Types of stabilizing devices
Before buying the device, you should familiarize yourself with the main types and features. Each has advantages and disadvantages, designed for different voltage levels and the number of devices. The principles of work differ.
Relay
The best option for private and country houses, apartments. Several magnetic windings are installed on the transformer. At the time of the voltage drop, a switching occurs between them, which allows you to save the voltage flow in the previous mode. The disadvantages include:
- change in energy flow in a stepwise mode (abruptly, intermittently);
- curvature of the sinusoidal voltage flow;
- low power at the time of recoil.
The cost of such devices is much lower than other models of stabilizers. Owner reviews are good, the device is enough for home networks.
Electronic
There are two types of stabilizers of electronic "filling" - triac and thyristor. In the first, switching between the windings in automatic mode is carried out by a small mechanism - a triac. The efficiency of the device is high, it works quickly. A significant plus for domestic use is the quiet operation. The second type is not so effective, it is usually used to stabilize home networks without much voltage. The most noticeable drawback is the cost.
Electromechanical
Other names - servomotor, servo-drive. The principle of operation - with the help of an electric drive, a carbon electrode moves along the windings, creating uninterrupted voltage.Often bought for domestic needs and small rooms (home, cottage, office). Pluses - the price, compactness, smooth switching. Cons - noise, low switching speed.
Ferroresonant
In recent years, rarely used due to the advent of more modern devices. The effect of ferroresonance occurs in the system of interaction of the transformer and capacitor. Large-sized devices, noisy, do not work with sharp and significant overloads. Advantages - long service life, the possibility of use in rooms with high humidity.
Inverter
Devices of this type are powerful and expensive. Used in everyday life and large industrial premises. The main difference is the crystal oscillator and controller, which convert the voltage at the input to direct current, and at the output to alternating. Simultaneous double formation allows you to work with different levels of current - from 115 to 300 volts. Advantages - no noise, small size, fast switching and regulation, other additional features (for example, protection of household appliances from excessive voltage).
Line Device Diagrams
The current stabilizer on the lm317 is a device operating according to a linear voltage switching circuit. Such microcircuits are used for networks where high efficiency and excessive power are not required. In particular, to support the operation of LEDs. Benefits:
- protection against sudden surges, excessive levels of electricity;
- polarity reversal of the current at the input element;
- lack of additional parts and devices.
The disadvantages include lower efficiency - the voltage obtained in excess of the necessary is processed into heating, so additional cooling is necessary.
For stable operation, a positive difference in currents at the input and output is required - linear stabilizers cease to function when they fall at 0.4V (even at 0.5V). Therefore, the PSU circuit on the lm317 with adjustable current and voltage is not used for large devices and "heavy" networks.
Main characteristics
The voltage regulator on the lm317 operates in a certain range of power supply. The limits are a minimum of 1.25V, a maximum of 37V. At the output, the voltage power does not exceed 1.5 Amperes, the error with unstable connection is up to 0.1%.
The voltage regulator on the lm317 microcircuit has additional internal protection systems: from short circuit faults, from thermal overvoltage, from excessive dissipation of "excess" voltage.
Thermal limitation is ensured by special microsensors that guarantee protection of the equipment from exceeding the dissipated power - if this happens, the device will simply turn off and not suffer.
Power and input voltage
For the current regulator to work on the lm317 circuit, the voltage at the input part should not be higher than 40 volts. In this case, the minimum current difference at the inputs and outputs must exceed 2 Volts.
For the voltage regulator to work on lm317, the circuit should not receive a load of more than 1.5A. If there is no additional cooling, the level will decrease. The approximate power is calculated by multiplying two indicators - the power of the electricity at the output and the difference in the potentials of the input and output.
At ambient temperatures up to 30 ° Celsius power dissipation up to 1.5 W is allowed (if there is no heat sink). At a normal level of heat dissipation, dispersion of up to 20W is allowed.
Device design
The stabilizer power supply circuit on the lm317 with current and voltage adjustment with a minimum arrangement has two resistors, the difference in resistance of which regulates the output voltage and capacitors. The average current value on the supporting elements is 1.25 V. The resistance should not exceed 240 Ohms.
The stabilizer body on the lm317 circuit is made of plastic. Possible options: TO 220 and 220FP, SOT23 and D2PAK. Internal protection systems allow the device to work in the event of a disconnection of the adjustment input.
Impulse drivers
Drivers with a pulse system are the same voltage stabilizers. AC voltage allows you to adjust the operation of the device. If the level is less than 2-3 Amperes, additional heat removal is not required.
Pulse devices "cut" the incoming current in order to obtain the desired voltage level at the output. It can work with high load networks. Cons - you need a separate power source, cost, external "excess" electromagnetic field. It is difficult to assemble at home.
Switching schemes
The power supply circuit on the lm317 with adjustable current and voltage allows you to use the stabilizer in networks with non-standard voltage. For the device to work, at least two resistors are required. The most important indicators are the voltage of the reference point, the current level at the output.
The simplest stabilized power supply
Voltage stabilizers are necessary not only to protect household and industrial equipment. In the laboratory, devices help to avoid excessive power flows and burnout networks. Therefore, beginners and professional technicians strive to use at least simple stabilizing blocks.
The main advantages:
- simple assembly;
- reliable work;
- inexpensive and affordable parts.
The disadvantages include low output efficiency, the use of large radiators, the large size of the device.
A standard device will require several elements:
- circuit lm317;
- transistor with a plastic case;
- diode;
- two resistors;
- two capacitors;
- diode bridge.
The minimum number of parts and simple design will allow you to quickly assemble a voltage regulator and use it for a small network.
Item metrics are not critical. For example, the resistors on R1 can have values from 30 to 50 Ohms, but do not install a diode.
Integrated Stabilizer Power Supply
Devices with an integrated operation system are used in voltage stabilizers, audio systems, amplifiers, power supplies and others. All structural details are connected by means of a silicon crystal so that their sequence constitutes a stabilizer. In electrical engineering, two types are used:
- using a semiconductor;
- using film elements (hybrid).
The standard circuit includes several typical parts: a reference source, an amplifier, a regulating element, a protective mechanism for disconnecting and preventing short circuits.
Integrated circuits are devices with a complete functional cycle. Each has entry, exit, and ground paths.
You can use such schemes only with certain voltage indicators. Permissible limits are from 5 to 24V, for current - less than 1A.
Integrated circuits have an output voltage limiter. Additional overheat protection is also installed.
Stabilizer circuit with adjustable power supply
The rectifier bridge in such devices allows you to convert an alternating current stream into a constant one. One of the capacitors filters the energy with ripple characteristics, the other makes the voltage transition smoother. This type makes it possible for the stabilizer to work at the level of low frequencies of direct current.
The choice of resistor is carried out according to the value of the rating acceptable for the stabilizer. The error should be minimal. The best option is an accurate calculation.
Application area
The stabilizers based on the LM317 chip are used to stabilize the main indicators of technical devices.Such a device is easy to assemble yourself, and a factory-made device is inexpensive. For this class it has excellent operational data and a useful life if there are no excessively strong power surges.
The disadvantage is the voltage limit - not more than 3V. The stabilizer based on the TO 220 enclosure is the most affordable model that is used in several areas:
- household (home) networks;
- laboratory conditions;
- LED lighting (LEDs).
Voltage stabilization systems based on the LM317 chip are reliable, simple and convenient devices. The cost is small, but the characteristics are positive. Such stabilizers are often used for LEDs in cars.
