The LM317 is more suitable than ever for the design of simple, regulated sources and electronics with a variety of output characteristics, both variable output voltage and fixed voltage output. electric shock loads.
To facilitate the calculation of the required output parameters, there is a specialized LM317 calculator, which can be downloaded from the link at the end of the article along with the LM317 datasheet.
Technical characteristics of the stabilizer LM317:
This inexpensive integrated circuit is available in TO-220, ISOWATT220, TO-3, and also D2PAK packages.
Below is an online calculator for calculating a voltage stabilizer based on LM317. In the first case, based on the required output voltage and the resistance of resistor R1, resistor R2 is calculated. In the second case, knowing the resistances of both resistors (R1 and R2), you can calculate the voltage at the output of the stabilizer.
For a calculator for calculating the current stabilizer on LM317, see.
The current stabilizer can be used in circuits of various battery chargers or regulated power supplies. The standard charger circuit is shown below.
This connection circuit uses a direct current charging method. As can be seen from the diagram, the charge current depends on the resistance of resistor R1. The value of this resistance ranges from 0.8 Ohm to 120 Ohm, which corresponds to a charging current from 10 mA to 1.56 A:
Below is a diagram of a 15 volt power supply with soft start. The required smoothness of switching on the stabilizer is set by the capacitance of capacitor C2:
Switching circuit with adjustable output voltage
Quite often there is a need for a simple voltage stabilizer. This article provides a description and examples of the use of an inexpensive (prices for LM317) integrated voltage stabilizer LM317.
The list of tasks solved by this stabilizer is quite extensive - this includes powering various electronic circuits, radio devices, fans, motors and other devices from the mains or other voltage sources, such as a car battery. The most common circuits are voltage-regulated.
In practice, with the participation of LM317, you can build a voltage stabilizer for an arbitrary output voltage in the range of 3...38 volts.
The voltage at the stabilizer input should not exceed 40 volts, and there is also one more condition - the minimum input voltage should exceed the desired output voltage by 2 volts.
The LM317 microcircuit in the TO-220 package is capable of stable operation at a maximum load current of up to 1.5 amperes. If you do not use a high-quality heat sink, this value will be lower. The power released by the microcircuit during its operation can be determined approximately by multiplying the output current and the difference between the input and output potential.
The maximum permissible power dissipation without a heat sink is approximately 1.5 W at an ambient temperature of 30 degrees Celsius or less. If good heat dissipation from the LM317 case is ensured (no more than 60 g), the power dissipation can be 20 watts.
When placing a microcircuit on a radiator, it is necessary to isolate the microcircuit body from the radiator, for example, with a mica gasket. It is also advisable to use heat-conducting paste for effective heat removal.
For accurate operation of the microcircuit, the total value of resistances R1...R3 must create a current of approximately 8 mA at the required output voltage (Vo), that is:
R1 + R2 + R3 = Vo / 0.008
This value should be taken as ideal. In the process of selecting resistances, a slight deviation (8...10 mA) is allowed.
The value of variable resistance R2 is directly related to the output voltage range. Typically, its resistance should be approximately 10...15% of the total resistance of the remaining resistors (R1 and R2), or you can select its resistance experimentally.
The location of the resistors on the board can be arbitrary, but for better stability it is advisable to place it away from the heatsink of the LM317 chip.
Capacitance C2 and diode D1 are optional. The diode protects the LM317 stabilizer from possible reverse voltage that appears in the designs of various electronic devices.
Capacitance C2 not only slightly reduces the response of the LM317 microcircuit to voltage changes, but also reduces the influence of electrical interference when the stabilizer board is placed near places with powerful electromagnetic radiation.
power unit - This is an indispensable attribute in the amateur radio workshop. I also decided to build myself an adjustable power supply, because I was tired of buying batteries every time or using random adapters. Here is its brief description: The power supply regulates the output voltage from 1.2 Volts to 28 Volts. And it provides a load of up to 3 A (depending on the transformer), which is most often enough to test the functionality of amateur radio designs. The circuit is simple, just right for a beginner radio amateur. Assembled on the basis of cheap components - LM317 And KT819G.
The case was taken from the computer's power supply. The front panel is made of PCB, it is advisable to install a voltmeter on this panel. I haven't installed it because I haven't found a suitable one yet. I also installed clamps for the output wires on the front panel.
I left the input socket to power the power supply itself. A printed circuit board made for surface-mounted mounting of a transistor and a stabilizer chip. They were secured to a common radiator through a rubber gasket. The radiator was solid (you can see it in the photo). It needs to be taken as large as possible - for good cooling. Still, 3 amperes is a lot!
Hello. I bring to your attention a review of the integrated linear adjustable voltage (or current) stabilizer LM317 at a price of 18 cents apiece. In a local store, such a stabilizer costs an order of magnitude more, which is why I was interested in this lot. I decided to check what was being sold at that price and it turned out that the stabilizer was quite high quality, but more on that below.
The review includes testing in voltage and current stabilizer mode, as well as checking overheat protection.
For those interested, please...
Testing:
Similar stabilizers are produced by many manufacturers, here.
The position of the legs is as follows: 
1 - adjustment;
2 - exit;
3 - entrance.
We assemble a simple voltage stabilizer according to the diagram from the manual: 
Here's what we managed to get with 3 positions of the variable resistor: 
The results, frankly speaking, are not very good. I wouldn't dare call it a stabilizer.
Next, I loaded the stabilizer with a 25 Ohm resistor and the picture completely changed: 
Next, I decided to check the dependence of the output voltage on the load current, for which I set the input voltage to 15V, set the output voltage to about 5V using a trimmer resistor, and loaded the output with a variable 100 Ohm wirewound resistor. Here's what happened: 
It was not possible to obtain a current of more than 0.8A, because The input voltage began to drop (the power supply is weak). As a result of this testing, the stabilizer with the radiator heated up to 65 degrees: 
To check the operation of the current stabilizer, the following circuit was assembled: 
Instead of a variable resistor, I used a constant one, here are the test results: 
Current stabilization is also good.
Well, how can there be a review without burning the hero? To do this, I reassembled the voltage stabilizer, applied 15V to the input, set the output to 5V, i.e. 10V dropped on the stabilizer, and loaded it at 0.8A, i.e. 8W of power was released on the stabilizer. The radiator was removed.
The result was demonstrated in the following video:
With that, let me take my leave, good luck!
The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.
I'm planning to buy +37 Add to favorites I liked the review +59 +88The LM317 adjustable three-terminal current regulator provides a load of 100 mA. The output voltage range is from 1.2 to 37 V. The device is very easy to use and requires only a pair of external resistors to provide the output voltage. Plus, the instability in terms of performance indicators has better parameters than similar models with a fixed output voltage supply.
LM317 is a current and voltage stabilizer that operates even when the ADJ control pin is disconnected. During normal operation, the device does not need to be connected to additional capacitors. The exception is when the device is located at a considerable distance from the primary filter supply. In this case, you will need to install an input shunt capacitor.
The output analog allows you to improve the performance of the LM317 current stabilizer. As a result, the intensity of transient processes and the value of the pulsation smoothing coefficient increase. Such an optimal indicator is difficult to achieve in other three-terminal analogues.
The purpose of the device in question is not only to replace stabilizers with a fixed output indicator, but also for a wide range of applications. For example, the LM317 current stabilizer can be used in high-voltage power supply circuits. In this case, the individual system of the device affects the difference between the input and output voltage. The operation of the device in this mode can continue indefinitely until the difference between the two indicators (input and output voltage) exceeds the maximum permissible point.
It is worth noting that the LM317 current stabilizer is convenient for creating simple adjustable pulse devices. They can be used as a precision stabilizer by connecting a fixed resistor between the two outputs.
The creation of secondary power sources that operate during short-term short circuits has become possible thanks to the optimization of the voltage indicator at the control output of the system. The program keeps it at the input within 1.2 volts, which is very low for most loads. The LM317 current and voltage stabilizer is manufactured in a standard TO-92 transistor core, operating temperatures range from -25 to +125 degrees Celsius.
The device in question is excellent for designing simple regulated blocks and power supplies. In this case, the parameters can be adjusted and specified in terms of load.
The adjustable current stabilizer on the LM317 has the following technical characteristics:
The device in question is most often used in LED power supplies. The following is a simple circuit that involves a resistor and a microcircuit.
The input voltage is supplied by the power supply, and the main contact is connected to the output analogue using a resistor. Next, aggregation occurs with the anode of the LED. The most popular current stabilizer circuit, LM317, described above, uses the following formula: R = 1/25/I. Here I is the output current of the device, its range varies between 0.01-1.5 A. The resistor resistance is allowed in sizes 0.8-120 Ohms. The power dissipated by the resistor is calculated by the formula: R = IxR (2).
The information received is rounded up. Fixed resistors are produced with a small spread of final resistance. This affects the receipt of calculated indicators. To resolve this problem, an additional stabilizing resistor of the required power is connected to the circuit.
As practice shows, during operation it is better to increase the dispersion area by 30%, and in the low convection compartment - by 50%. In addition to a number of advantages, the LM317 LED current stabilizer has several disadvantages. Among them:
The use of pulse stabilizers will help to avoid problems in operating the device.
It is worth noting that if you need to connect a powerful LED element with a power of 700 milliamps, you will need to calculate the values using the formula: R = 1.25/0.7 = 1.78 Ohm. The dissipated power will accordingly be 0.88 watts.
The calculation of the LM317 current stabilizer is based on several connection methods. Below are the basic diagrams:
It is worth noting that a simple charger can also be assembled based on the microcircuit of the device in question. You will get a standard linear stabilizer with an adjustable output voltage. The microassembly of the device can function in a similar role.
The powerful stabilizer on the LM317 has a number of analogues in the domestic and foreign markets. The most famous of them are the following brands:
