The current stabilizer for LEDs is used in many lamps. As with all diodes, LED is inherent nonlinear volt-ampere dependence. What does it mean? When raising the voltage, the strength of the current slowly begins to pick up power. And only when the threshold is reached, the brightness of the LED becomes saturated. However, if the current does not stop growing, the lamp can burn.

The correct LED work can be provided only due to the stabilizer. This protection is also necessary due to the scattering of the threshold values \u200b\u200bof the LED voltage. When connecting over a parallel circuit, the bulb may simply be easy to burn, since they have to miss an invalid current for them.

Types of stabilizing devices

By the method of limiting the strength of the current, devices of a linear and pulsed type are distinguished.

Since the voltage on the LED is a constant value, then current stabilizers are often considered to be LED power stabilizers. In fact, the latter is directly proportional to the voltage change, which is characteristic of linear dependence.

The linear stabilizer heats up the greater, the more the voltage is attached. This is his main defects. The advantages of this design are due to:

• lack of electromagnetic interference;
• simplicity;
• low cost.

More economy devices are stabilizers based on a pulsed converter. In this case, the power is pumped up portion - as needed for the consumer.

Linear Device Schemes

SAMI simple scheme Stabilizer is a scheme built on the basis of LM317 for the LED. The latter is an analogue of Stabilon with a specific working current that it can skip. Given the low current strength, you can collect a simple device yourself. The simplest driver lED lamps And the tapes are collected in this way.

The LM317 microcircuit is no longer one decade is a hit among beginner radio amateurs due to its simplicity and reliability. On its basis, you can collect the adjustable block driver and other BP. This requires several external radio components, the module works at once, no settings are required.

Integral stabilizer LM317 as no other suitable for creating simple adjustable power supplies for electronic devices with different characteristics, both with adjustable output voltage and with specified load parameters.

The main purpose is to stabilize the specified parameters. The adjustment occurs in a linear way, in contrast to the pulse converters.

LM317 are produced in monolithic housings performed in several variations. The most common model TO-220 with LM317T marking.

Each conclusion of the microcircuit has its purpose:

• Adjust. Input to regulate the output voltage.
• Output. Input for the formation of output voltage.
• Input. Input for supplying the supply voltage.

Technical indicators of the stabilizer:

• Output voltage in the range of 1.2-37 V.
• Protection against overload and KZ.
• Output voltage error 0.1%.
• Inclusion scheme with adjustable output voltage.

Scattering power and device input voltage

The maximum "Planck" of the input voltage should be no more specified, and the minimum is higher than the desired output to 2 V.

The chip is designed for stable operation at maximum current to 1.5 A. This value will be lower if you do not apply a high-quality heat sink. The maximum allowable dispersion of power without the latter is approximately 1.5 W at ambient temperature not more than 30 0 C.

When installing the chip, the housing is insulated from the radiator, for example, with a mica laying. Also, the effective heat removal is achieved by the use of heat-conducting paste.

Short description

Briefly describe the advantages of the LM317 radio electronic module used in current stabilizers, as follows:

• the brightness of the light stream is provided by the range of output voltage 1, 37 V;
• the output indicators of the module do not depend on the rotation frequency of the electric motor shaft;
• supporting the output current to 1.5 A allows you to connect several electrical receivers;
• the error of oscillations of the output parameters is 0.1% of the nominal value, which is a guarantee of high stability;
• there is a function of protection for the limitation of current and cascade shutdown when overheating;
• the microcircuit body replaces the ground, so the number of mounting cables decreases with an external attachment.

Inclusion schemes

Of course, the most easy way to restrict for LED lamps will be the sequential inclusion of an additional resistor. But this tool is suitable only for low-power LED.

Simplest stabilized power supply

To make the current stabilizer takes:

• microcircuit LM317;
• resistor;
• mounting agents.

We collect the model according to the following scheme:

The module can be used in different schemes charger or regulated IB.

Power supply on an integral stabilizer

This option is more practical. LM317 limits the current consumed, which is set by the R. resistor

Remember that the maximum allowable current value that is needed to control LM317 is 1.5 and a good radiator.

Scheme of stabilizer with adjustable power supply

Below is a diagram with an adjustable output voltage of 1.2-30 V / 1.5 A.

The alternating current is converted to a constant rectifier (BR1). Condensor C1 filters pulsating current, C3 improves transitional characteristics. This means that the voltage stabilizer can work perfectly at constant toke. on the low frequencies. The output voltage is regulated by the R1 slider from 1.2 volt to 30 V. The output current is about 1.5 A.

The selection of resistors at rates for the stabilizer should be carried out on accurate calculation with a permissible deviation (small). However, arbitrary placement of resistors on circuit boardBut it is desirable for better stability to place them away from the LM317 radiator.

Application area

The LM317 microcircuit is an excellent option for use in stabilization mode of basic technical indicators. It has simplicity of performance, inexpensive cost and excellent performance. The only drawback is the voltage threshold value of only 3 V. Case in the style of T220 is one of the most affordable models that allows you to dissipate the heat quite well.

The microcircuit is applicable in devices:

• current stabilizer for LED (including for LED tapes);
• Adjustable.

A stabilizing scheme, built on the basis of LM317 simple, cheap, and at the same time reliable.

Comments (16):

# 1 root March 28 2017

Additions were added to the scheme:

• The transistors for alignment of currents have been added to the transistors' emitter circuit;
• Added capacitors C3 and C4 (0.1μF ceramics).

Capacity C1 is better to make up of several electrolytic capacitorsIf you need a high current, it is recommended 2 pieces of 4700mkf and more.

CT819 transistors can be replaced by foreign MJ3001 or others.

# 2 Victor September 12, 2017

R2-what type, joint venture ... or. Smem is not bad! Thank you !!!

# 3 root September 12 2017

Resistor R2 - variable resistance, of any type, with a power of 0.5W and more. If there is no resistance to 3.3K, you can set 6,8k or other (up to 10k).

# 4 Dmitry October 25 2017

Thanks for the lessons are very useful.

# 5 Eugene November 25 2017

What about the protection against overload / kz?

# 6 root November 26 2017

The present scheme does not protect against CW and current overload. Without improving the scheme at its output it will not prevent installing fuse.

# 7 Andrius December 15 2017

collected the scheme But something falls the current at the exit. Thetrans 300.4A feed 31 volts A at the output with a load of 6 volt 3 voltage. Maybe something wrong. The transistors changed the LM too - it does not help.

# 8 root December 15 2017

Carefully check all the installation, especially the correctness of the microcircuit and transistors.
COFCOL CHOCHCH LM317:


According to transistors in plastic and metal housings - KT819 - characteristics and basement.

# 9 Andrius December 15 2017

all checked many times. The chip is correctly connected to the transistor too. also changed the chip, transistors. Nothing helps do not even know what else can be done.

# 10 Alexander Commonsister December 16 2017

I thank #root for the mixed internal circuit of the chip: I was looking for everywhere, but unsuccessfully. At the 12th crop it will be similar.

# 11 Alexander Commonsister December 17 2017

As for the internal scheme LM317: how to replace the current source: Speak two (or more) silicon diodes? Is it possible to replace the transistors on the internal scheme for one composite brand, say, kt827vm? How to replace the operational amplifier? How to build current protection? - And while I wrote questions, I immediately found the answer: use the field transistor.

# 12 ROOT December 17 2017

Alexander, below schematic scheme Crystal chips LM117, LM317-N from datashet (site Ti.com - Texas Instruments):

# 13 Alexander Commonsister December 17 2017

Thank you: Very reminds the CR142NE scheme. But there are no denominations.

# 14 Igor December 26 2017

Is it possible to apply the CT827A transistors in the scheme?

# 15 Alexander Commonsister December 27 2017

Igor: Surely it is possible, however, after the operator (see post # 8) in the base chain before the protection circuit, it is likely to include a quenching resistor, the denomination of which depends on the supply voltage: the main thing is that on the basis of the emitter there is no more five volts. Current Protection Current Protection Node is likely to be replaced with Z147A Stabilitron.

# 16 Andrey February 06 2018

Hello, the first time I collect the power supply - found the old transformer in the garage. To do it according to this scheme. Please tell me what leg a variable resistor Where goes.

A beginner radio amateur simply can not do without at least the simplest power supply. When developing or configuring a particular device, an adjustable power supply is not a replace attribute. But if you are a novice amateur, and you cannot afford a dear hood power supply, then this article will help you to fill your need

Power supply on the LM317T chip, scheme:

On the Internet there is an innumerable set of schemes of various power supplies. But even at first glance, light schemes, in the configuration process, are not so easy. I recommend that you consider very simple in the setting, cheap and reliable diagram of the power supply unit on the chip stabilizer LM317T, which adjusts the voltage from 1.3 to 30 V and provides a current 1a (as a rule, this is sufficient for simple radio amateurs) Figure No. 1.

Figure No. 1 is an electrical circuit diagram of an adjustable power supply.

R1 is about 18 com (you need to pick up the current of the LED).
R2 - You can not fall in - it is necessary if you need to obtain non-standard voltage adjustment limits. You just pick it up in such a way that the sum R2 + R3 \u003d 5k.

R3 - 5.6 com.
R4 - 240 ohms.
C1 - 2200 μF (electrolytic)

C2 - 0.1 μF
C3 - 10 μF (electrolytic)
C4 - 1 μF (electrolytic)
DA1 - LM317T.

The main element in the scheme is the LM317T chip, you can easily look in the manual on the microcircuit. The only thing that should be noted separately is that it is necessary to cling to the radiator (Figure 2) that the chip does not fail.

Figure 2 is an example of a radiator.

The maximum current of it in the documentation 1.5 A - but I do not recommend having to drive it into such fade modes of work.
I recommend using a transformer, too, with a reserve of current (current 3a), in order in case of a sharp throw of the current, it has not failed.
Each radio amateler makes printed circuit boards as he yourself - but if you are too lazy to trace it - you can use my printing board of Figure No. 3, which is available at this link or on this link. Files can be opened using the Sprint-Layout 5 program.

Figure No. 3 - Board Printing and Assembly Drawing

Before you start making my option wiring the board - review it again and analyze !!! I traced a fee for the method of photolithography, so unfold it as you need. I tried to make a fee the most universal for this scheme and did it to your needs. If you do not bury the R2 resistor - then instead you just need a jumper.

P.S.: I tried to visually show and describe not cunning tips. I hope that at least something will be useful to you. But this is not all that it is possible to invent, so dare, and look through the site

How can you connect a voltmeter and an ammeter to this scheme

All resistance in the scheme is best to put half-life, it is almost a guarantee of the stable performance of the scheme, even in the limit operating conditions. R2 resistor can be completely excluded from the scheme, I left a place for it on those cases when you need to receive non-standard tension. And also, thoroughly fighting on the Internet, I found a special calculator for recalculating LM317, namely resistors in the voltage adjustment control circuit.

Special Calculator Window for Calculation LM317 Control Divider

Resistors R3 and R4 are an ordinary voltage divider, so we can pick it up under the resistors that we have at hand (in the specified limits) - it is very convenient and allows you to easily adjust the LM317T work under any voltage (top May vary from 2 to 37 V). For example, you can choose the resistors so that your power supply can be adjusted from 1.2 to 20V - it all depends on the transition of the R3 and R4 divider. The formula on which the calculator works, you can find out the reading datashet on LM317T. Otherwise - if everything is assembled correctly, the power supply is immediately ready for work.

Power Supply - This is an indispensable attribute in a radio amateur workshop. I also decided to collect an adjustable BP, as it was tired of buying batteries each time or enjoy random adapters. Here is his brief description: PB controls output voltage from 1.2 volt to 28 volts. And provides a load of up to 3 A (depends on the transformer), which is most often enough to test the efficiency of amateur structures. The scheme is simple, just for a novice radio amateur. Assembled on the basis of cheap components - LM317. and Kt819g.

LM317 adjustable power supply circuit

List of schema elements:

• Stabilizer LM317.
• T1 - Transistor Kt819g
• TR1 - Power Transformer
• F1 - 0.5a 250V fuse
• BR1 - Diode Bridge
• D1 - Diode 1N5400
  
• LED1 - LED of any color
  
• C1 - Electrolytic Condenser 3300 μF * 43V
  
• C2 - Ceramic Condenser 0.1 μF
  
• C3 - electrolytic condenser 1 μF * 43B
  
• R1 - 18K resistance
  
• R2 - 220 ohm resistance
  
• R3 - resistance 0.1 Ohm * 2W
  
• P1 - Strong Resistance 4.7K

COLOR COVERCHES AND TRANSISTOR

The case took from the computer's BP. Front panel made of textolite, it is desirable to install a voltmeter on this panel. I did not install because I have not yet found a suitable. Also on the front panel installed clips for output wires.

The inlet socket left for the power of the BP itself. The printed circuit board made for the attachment of the transistor and the stabilizer chip. They were secured on a general radiator through a rubber gasket. The radiator took a solid (in the photo it can be seen). It must be taken as much as possible - for good cooling. Still, 3 amps are a lot!

The power supply is one of the most important devices in the radio amateur workshop. Especially with batteries and with batteries each time it is silent somehow tired. The BP considered here regulates the voltage from 1.2 volt to 24 volts. And load up to 4 A. for greater current, it was decided to establish two identical transformers. Transformers are connected in parallel.

Details for adjustable power supply

1. Stabilizer LM317 TO-220 housing.
2. Silicon transistor, P-N-P KT818.
3. Resistor 62 ohms.
4. Electrolytic condenser 1 μF * 43B.
5. Electrolytic condenser 10 μF * 43B.
6. Resistor 0.2 Ohm 5W.
7. Resistor 240 ohms.
8. Strong resistor 6.8 com.
9. Condenser electrolytic 2200 μF * 35V.
10. Any LED.

Power unit circuit

Protection block diagram

Block diagram rectifier

Details for building protection against KZ

1. Silicon transistor, N-P-N KT819.
2. Silicon transistor, N-P-N KT3102.
3. Resistor 2 Ohm.
4. 1 com resistor.
5. 1 com resistor.
6. Any LED.

For the housing of the adjustable power supply, two housings were used, from ordinary computer Block Nutrition. In place from the cooler, a voltmeter and ammeter were supplied.

For additional cooling, a cooler was installed.

But you can join the scheme just mounted installation. Enclosures are connected using two bolts.

The nuts were glued, to the lid of the thermo glue cover. To cool the stabilizer and transistors, a radiator from the computer was used, which blew the cooler.

For the convenience of transferring the power supply, the knob from the hubled in the written table was screwed. In general, the resulting power supply is very like. Its power is enough to power almost all circuits, chip check, and charging small batteries.

The IP scheme does not need to be configured, and with proper spike, it will earn right away. Article author 4EI3. E-mail [email protected]

Discuss a BP article on LM317 with a security unit