A voltage regulator in the car

The stabilizer of a voltage of an onboard network

Description of the nuances of assembling a 12 volt voltage regulator for the car, the list of necessary parts, 3 variants of circuits. + Test for self-testing. Parsing the top 5 questions on the topic and the top 3 soldering irons for boards.

  1. Why would you install a 12 volt stabilizer on your vehicle? a) The car’s mains gives an unstable voltage. It depends on how much the battery is charged. The voltage varies between 11.5 and 14.5 volts. But LED lights only require 12 volts. To supply the right voltage and put the CH. b) LED lamps work on 18 volts. In order for them to function when plugged into a car, you have to supply an additional load through a stabilizer.
  2. Why do LED bulbs often burn out without a stabilizer? a) The main reason is the poor quality of the LED manufacturer. b) Because of the surge voltage on them.
  3. In what case, in addition to the stabilizer will have to connect an aluminum heat sink? a) If the car will be installed more than 10 LEDs. b) When installing LED bulbs of different colors on the car.
  4. How are the LEDs connected? a) 3 LEDs are connected in series to a resistor, and then the assembled set is connected in parallel to the next LEDs. b) 3 LEDs are connected in parallel to a resistor, and then the assembled set is connected in series to the next LEDs.


  1. a) Depending on how charged the battery is, the LED lamps will have a fluctuating voltage of 11.5 to 14.5. This is why you connect a CH to the lamps – to get a constant voltage equal to 12 volts (this is the figure LEDs need).
  2. b) LEDs are not designed for voltage spikes that come from the battery, so they soon burn out without a stabilizer.
  3. a) If more than 10 LEDs are installed on the car, it is advisable to equip the circuit with an aluminum heat sink.
  4. b) First 3 LEDs are connected in series to a resistor, and then take a new coupler and already connect them in parallel to each other.

Car owners often install LED lights on their car. But the bulbs quite often fail, and all the beauty created fades at once. It is explained by the fact that the LED bulbs do not work properly, if you just connect them to the power grid. It is mandatory to use special stabilizers for them. Only then the lamps will be protected from voltage fluctuations, overheating, breakage of important components. To install a voltage stabilizer on your car, it is necessary to understand this issue in detail and study a simple circuit, which will be able to assemble their own hands.

Definition: a 12 volt voltage regulator for the car is a small device designed to dampen the excessive voltage of the car, coming from the battery. As a result, connected LED lights receive a constant load of 12 volts.

Selecting a 12 volt stabilizer

The car’s on-board network provides power from 13 V, but the LEDs need only 12 V to work. That is why it is necessary to install a voltage regulator, which will provide exactly 12 V at the output.

Installing this equipment will provide normal conditions for the LED lighting, which long time will not fail. When choosing stabilizers, motorists face problems, because there are so many designs, and they all work differently.

You should choose a stabilizer that:

  1. Will function properly.
  2. Provide reliable protection and safety of lighting equipment.

A simple 12-volt voltage regulator with your own hands

If you have even a little skill in assembling an electrical circuit, then the voltage regulator is not necessary to buy in prefabricated form. To make a homemade device man spend 50 rubles or less, a ready-made model is somewhat more expensive. There is no point in overpaying, because the result will be a high-quality device that meets all the necessary requirements.

The simplest, but functional stabilizer can be made with your own hands without much effort. The pulse device is very difficult to assemble, especially for the beginner, and therefore it is worth considering linear stabilizers and amateur schemes on it.

The simplest 12 volt voltage regulator is assembled from a circuit (ready-made), as well as a resistance resistor. It is desirable to use an LM317 chip. All parts will be attached to a perforated panel or universal printed circuit board. If you assemble the device correctly and connect it to your car, you can provide good lighting – the bulbs will stop blinking.

LM317 wiring diagram

Parts list CH 12 V

To make a voltage stabilizer with your own hands, you should find or buy the following parts:

  1. The board – 35 by 20 mm.
  2. Microcircuit LD 1084.
  3. Diode bridge RS407. If you do not have one of these, then pick up any small diode for reverse current.
  4. A power supply with a transistor and two resistors. This equipment is needed to cut off the end when the low beam or high beam is turned on.
Making a marker with flux for soldering wires and parts with our own hands

Three LEDs should be connected in series with a current-limiting resistor to equalize the electric current. This set should then be connected in parallel to the next set of bulbs.

How to make a 12 volt voltage regulator for LEDs in a car on the chip L7812

To assemble a quality voltage regulator, you can use a three-pin DC voltage regulator, which is available in a series of L7812. This device will power not only individual bulbs in the car, but also an entire strip of LEDs.

  1. L7812 chip.
  2. A 330 uF 16 V capacitor.
  3. Capacitor with 100 uF of 16 V.
  4. A 1 amp rectifier diode. You can use 1n4001 or a Schottky diode.
  5. 3mm heat shrink.
  6. Connecting wires.
Assembly procedure:
  1. Shorten one leg of the stabilizer a little.
  2. Use solder.
  3. To the short leg we add the diode and then the capacitors.
  4. Put a heat shrink on the wires.
  5. We are soldering the wires.
  6. Put on the heat shrink and press it with a construction hair dryer or a lighter. It is important not to overdo it and not to melt the heat shrink.
  7. Power on the left side of the input, on the right side there will be an output for the LED strip.
  8. Carry out a test – turn on the light. The strip should light up, its service life will now increase.

This is how to make a 12 volt voltage regulator with your own hands.

Circuit of the 12 volt voltage regulator for LEDs in the car with own hands on the LM2940CT-12.0

Also to assemble a quality voltage regulator for the car use the circuit LM2940CT-12.0. As a case we use absolutely any material, except wood. If you plan to install more than 10 LED lamps in the car, then it is desirable to attach an aluminum heat sink to the stabilizer as well.

Perhaps some have had experience with such equipment, and will say that there is no need to use additional parts – directly connect the LEDs and enjoy the work. This can be done, but in this case, the bulbs will be constantly in adverse conditions, and therefore will soon burn out.

The advantage of all the above circuits of the voltage regulator 12V own hands – ease of assembly. To assemble the stabilizer, you do not need to have any special skills. But if the provided pictures cause only bewilderment, then with your own hands should not try to assemble a circuit.

It is also important to know three nuances of how to assemble a 12 volt voltage regulator with your own hands

  1. LEDs should preferably be connected through a current regulator. Thus it will be possible to balance the fluctuations of the electric network, and the owner of the car will not worry about current surges.
  2. Requirements for power supply must also be observed, because, thus, your own assembled stabilizer will be able to properly adjust to the electrical network.
  3. It is desirable to assemble such a unit, which will provide decent stability, reliability and stability – the stabilizer should hold for many years. That is why you should not cheap out on components – buy from good electronics stores.

How to avoid 3 mistakes when soldering the circuit

  1. Before starting all the soldering work, be sure to choose the most appropriate soldering machine, to assemble the chip. The old one which is at home or in a garage will be suitable only for experienced people. A beginner will spoil the board not being able to cope with the power. The most suitable voltage range for connecting boards and wires is 15-30 watts. Do not use more power, otherwise the board will burn out and you will have to start all over again with new parts.
  2. Before you start connecting the parts by soldering, make sure that the circuit is well cleaned. For quality treatment use a simple compound – mix any soap with clean water. After a clean cloth is dipped in the prepared solution and the board is wiped very well over the entire surface. If traces of soap are left on the metal, wipe them gently with a dry cloth. The boards often have quite dense deposits on them. To get rid of them, you will have to go to a store with electrical goods and buy a special cleanser. The salespeople will tell you everything you need. Treat the area until a slight metallic sheen appears.
  3. The contacts on the board are placed in the correct order – first work with small resistors, and then move on to the large parts. If you fix all the large parts first, it will be very inconvenient to connect the small parts – the large components will get in the way.
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Do not neglect the tips. They will create a better connection, and thus the longevity of the stabilizer.

Top 3 soldering irons for boards

To simplify the work of soldering the stabilizer, it is desirable to buy a quality soldering iron. There are units from good and trusted manufacturers available in stores that you should pay attention to:

  1. Ersa is a German company. The product is very good and reliable, but expensive, and therefore for the home not everyone can afford.
  2. Chinese company Quick. The quality is high, and the price is reasonable.
  3. Luckey. The most budget variant. Do not leave the device on unattended – a fire is possible.

The 10w soldering iron is enough to make a simple microboard. When buying, study the handle – it should not get hot quickly. Wood is ideal. Plastic will quickly become hot, ebonite is heavy, and therefore it is difficult to work with small parts.

It is desirable to choose the tip from copper – it is easy to clean from fouling after work. The stingers come in different shapes and are sold in sets. It is not useful for a beginner, but for experienced people it will be convenient to use tips of different configurations.

Voltage regulators for cars

LEDs do not like voltage fluctuations, it is a fact. They do not like it for the reason that LEDs do not behave like lamps or other linear devices. Their current varies with voltage in a non-linear way, so for example doubling the voltage increases the current through the LEDs is not twice as much. For this reason they overheat, quickly degrade and fail.

Most of the diodes used in the car have built-in resistance, which is designed for 12 volts. But the voltage of your car’s onboard network is never 12 volts (except with a dead battery), plus it’s not as stable as you’d like it to be. If you use inexpensive Chinese diode devices in your car without stabilizing them first then they will start blinking fast enough and then they will stop shining.

I have faced such a problem – LEDs in my headlights started blinking, because I was too lazy to stabilize them.

There are many commercially available circuits for 12 volt fixtures. The most common one you can find on the shelves is a KR142EN8B or similar. This circuit is designed for a current of up to 1.5A, but for a greater effect, you need to connect it with input and output capacitors.

The standard circuit assumes 0.33 and 0.033µF capacitors (if memory serves me correctly). But personally I decided to make the switch using 4 capacitors: 470μF and 0.47μF for the input and correspondingly 10 times less capacitance for the output. I don’t remember anymore, but somewhere on the forums I met exactly this connection, I decided to apply it.

I decided to solder all the elements directly to the IC so that it would be easy to install in the car.

Circuit and elements

Circuit and elements

To the chip soldered in addition to the capacitors there are two wires, respectively input and output. The mass will come through the chip mount. The middle leg of the microcircuit is used only for the capacitor legs. I did not take the wire out of it, because it is connected to the circuit case. I decided to fill it all with glue and then wrap it in heat shrink.

The Microcircuit and the heat shrink.

In the car you can attach via a self-tapping screw to the body.

This post does not pretend to be something super-mega technological but it might be useful for someone 🙂

Instead of the KR142EN8B you can use L7812CV, the circuit is similar. If you look at the standard circuit and compare it with mine, then there are questions “why exactly such capacitors?

Let me explain: the standard circuit of the power supply involves only voltage stabilization, but does not save from the voltage sag (short-term), so in the scheme were introduced electrolytes of sufficiently high capacity to smooth out such sags.

In theory, of course, the battery in the car should perform the role of a surge filter, but sometimes there are surges that the battery just does not have time to catch. For example, when the spark is applied to the spark plug, a considerable current passes through the coil, which perfectly draws down the voltage in the on-board network.

Copper terminals for the car with their own hands.

The on-board voltage regulator is designed to protect the complex automotive electronics from sudden voltage fluctuations. This reliable and inexpensive device eliminates equipment failure due to power surges.

Particularly when installing the GPS tracking system equipment on the large automotive equipment with onboard voltage 24V (large trucks, tractors, special equipment), the engineers of our company recommend using such stabilizer.

Although NAVIXY VT series GPS trackers are designed for installation in cars with onboard voltage ranging from 8-35V, i.e. suitable for cars with 12V and 24V, in practice there are situations when the use of stabilizers is necessary. For example, when the installation is made in cars of domestic production or budget brands, which do not have a special subsystem power car electronics (audio system, etc.).

FAQ What to buy? Voltage regulator or current regulator? Note to self!

Every time, reading new blog posts in the community I run into the same mistake – they put the current regulator where you need a voltage regulator and vice versa. I will try to explain on my fingers, without going into the maze of terms and formulas. It will be especially useful for those who put a driver for high-power LEDs and feed a lot of low-power LEDs with it. For you – a separate paragraph at the end of the article. =)

I want to apologize to everyone whose drawings suddenly ended up in this article. Thank you for your hard work, feel free to tag them in the comments. I will add authorship, if necessary.

First, let’s get the concepts straight:

Voltage stabilizer Based on the name, it stabilizes the voltage. If it is written that the regulator 12V and 3A, it means that it stabilizes the voltage 12V! And here 3A – this is the maximum current that can give the stabilizer. Maximum! And not “always gives 3 amps”. That is, it can give out 3 milliamps, or 1 amp, or two amps… As much as your circuit eats, so it gives out. But no more than three. That’s the main thing.

And now I will move on to describing the types of voltage regulators:

Linear voltage regulators (the same KREN or LM7805/LM7809/LM7812, etc.)

The most common kind. They can not operate at voltages lower than the voltage specified on its belly. That is, if the LM7812 stabilizes the voltage at 12 volts, it needs at least about 1.5 volts more at its input. If it is less, then the output of the stabilizer will be less than 12 volts. It can’t take the missing volts from nowhere. That is why it is a bad idea to stabilize auto voltage with 12 volt RACs. As soon as the input voltage is less than 13.5 volts, it starts to give less than 12 volts at the output as well. Another disadvantage of linear stabilizers – a strong heating at such a good load. That is, in country language – everything above the same 12 volts, it turns into heat. And the higher the input voltage, the more heat. Up to the temperature of frying eggs. If you load it a bit more than a couple of small LEDs and that’s it, you get a great iron.

Pulse stabilizers are much cooler, but also more expensive. Usually for the average buyer it already looks like some kind of circuit board with parts.

There are three kinds: step-down, step-up and omnivorous. The coolest ones are omnivorous. They don’t care if the input voltage is lower or higher than necessary. They automatically switch to increasing or decreasing voltage and keep the set voltage at the output. And if it is written that it can have from 1 to 30 volts at the input and the output will be stable 12 volts, then it will be so. But more expensive. But cooler. But more expensive… If you don’t want linear regulator iron and huge heatsink for cooling you should buy a switching regulator. What’s the conclusion on voltage regulators? You set hard volts – and current can float as you want (within certain limits of course)

Current Stabilizer As applied to LED’s it is also called an “LED driver”. Which is also true.

Here, for example, is a ready made driver. Although the driver itself is a small black eight-legged chip, but usually the driver is called the entire circuit at once.

It gives the current. Stable! If it says that the output is 350mA, then you can bet your ass it will be exactly like that. But the volts on its output may vary depending on the voltage that the LEDs need. This means you don’t regulate them. The driver will do everything for you based on the number of LEDs you have. If it is very simple, I can only describe it like this. =) And the conclusion? You set the current – and the voltage can float.

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Now to the LEDs. After all, it’s all about LEDs.

An LED is powered by current. It doesn’t have a parameter called TENSION. There is a parameter – the voltage drop! That is, how much is lost on it. If it says 20mA 3.4V, this means that it needs no more than 20 milliamps. And that means it will lose 3.4 volts. It doesn’t need 3.4 volts to power it, it just gets “lost” on it! So you can power it from 1000 volts, as long as you don’t supply more than 20mA. It will not burn out, will not overheat, and will shine as it should, but it will have 3.4 volts less. That’s the science. Limit the current and it will be full and will shine happily for a long time.

Here we take the most common connection of LEDs (this is used in almost all strips) – 3 LEDs and a resistor are connected in series. We supply from 12 volt. The resistor limits the current on the LEDs so they do not burn out (I do not write about the calculation, there are a lot of calculators on the Internet). After the first LED is left 12-3.4 = 8.6 volt. This is enough for us for now. At the second will be lost another 3.4 volts, so there will be 8.6-3.4=5.2 volts. That’s enough for the third LED as well. And after the third will be 5.2-3.4=1.8 volts. And if you want to put the fourth, it will not be enough. But if you power it from 15 volts instead of 12V, then it will be enough. But we should take into account that the resistor will also need to recalculate. Well actually we came smoothly to…

The simplest current limiter is a resistor. They are often put on the same ribbons and modules. But there is a minus – the lower the voltage, the less will be the current on the LED. And vice versa. So if your network voltage jumps like horses over the barriers at show jumping competitions (and in cars it usually is), then first stabilize the voltage, and then limit the current to the same 20mA with a resistor. And that’s it. We do not care about voltage spikes (voltage regulator works), and LED is full and shines to the joy of all. That is – if you put a resistor in the car, you need to stabilize the voltage.

You can not stabilize, if you calculate the resistor for the maximum possible voltage in the network car, you have a normal on-board network (not the Chinese-Russian tazoprom) and make the reserve current at least 10%. Well, besides resistors can be put only up to a certain value of current. After a certain threshold resistors start to heat up like hell, and you have to greatly increase their size (resistors 5W, 10W, 20W, etc.). Smoothly turning into a big iron.

Another option is to put something like LM317 as a limiter in current stabilizer mode.

But they also get warm, because it is also a linear regulator (remember I wrote about RACs in the paragraph about voltage regulators?). And then created…

Impulse current regulator (or driver).

It includes everything you need. And it almost never gets hot (only if you overload it or if the circuit is wrong). That is why they are usually used for LEDs with power more than 0.5W. The warmest element in the circuit is the LED itself. But it is written in the wording of its name to be warm. The main thing is not to overheat above a certain temperature. Otherwise, if you overheat, the LED crystal begins to degrade wildly and it gets dull, begins to change color and stupidly dies (hello, Chinese light bulbs!).

Well, in conclusion – to what I always try to prove in discussions. And I do. Except that everyone separately to explain the same thing – language would fall off. So I will try again in this article.

I always see the following picture – they use drivers for high power LEDs (say 350mA) and put several branches of LEDs without any limiting resistors and stuff like that. And these people are not lamers but they make the same mistake over and over again. I will tell you why this is bad and what it can lead to:

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From Ohm’s law for a complete circuit: The current in an unbranched circuit is equal to the sum of the currents in its parallel sections. Many people think so – “each branch is 20mA, I have 20 branches. The driver is supplying 350mA, so each branch will have even less – 17.5mA. Bingo!” Well, it’s not bingo, it’s asshole. Why?

The current in each branch will be equal, if you have perfect LEDs with exactly the same parameters. Then the current in all the branches will be the same, and there is no need for current limiters – just divide the total current by the number of identical branches. But this is only in fairy tales. If the parameters are slightly different – you’ve got 19mA in one branch, 17mA in the other, 20mA in the third… Total amount of current remains unchanged – 350mA, but the branches are going crazy crap. You can’t tell at a glance, they look the same… And then you have one branch, the most voracious, starts to warm up more than the others. And it eats more. And it gets even hotter. And then, boom, it goes out. And all those milliamps scattered to the other branches. And then another branch, which seemed to be burning fine not long ago, goes on and goes out after it. And already twice as much current goes to other branches, because the total current is rigidly set at 350mA. This process is avalanche-like, and that’s why all 350mA have been absorbed by remaining LED’s and nobody has saved them… If we had had a separate stabilizer (at least a banal resistor) for each branch, it would have kept working.

That’s exactly what I’m talking about. This picture shows 1W LEDs, but with any other LEDs the picture is the same.

This is exactly what we see in Chinese modules and cucurbits, which burn up like matches after a week/month of operation. Because LEDs have a hell of a spread, and the Chinese save on drivers cooler than anyone else. Why don’t branded modules and lamps from Osram, Philips, etc. burn? Because they make quite a powerful rejection of LEDs and from all the wildest number of produced LEDs remains 10-15%, which are almost identical in parameters and from them you can make such a simple form, which many are trying to do – one powerful driver and many identical chains of LEDs without drivers. But only in terms of “bought LEDs on the market and soldered yourself” as a rule it will not be good for them. Because even the “non-Kitai” will have variation. May be lucky and work long, or may not.

And the current driver compared to the voltage regulator and kopeck resistors is usually more expensive. Why shoot a target for a small-caliber rifle from a tank? We can hit the target, no question. But we will leave a crater along with it. =))

And just – to do the right thing and do “look how I saved money, and the rest are fools” – it’s a few different things. Even very different. Learn to do not as the proverbial Chinese, learn to do beautifully and correctly. This is said long ago, and not by me. I just tried for the hundred and fifty thousandth time to explain the elementary truths. Forgive me if I explained incorrectly =)

Here’s a perfect illustration. Don’t you think I wanted to save money and reduce the number of drivers by 3-4 times? But it’s right and it will work long and happy.

And finally, to those for whom even this statement was too abstruse. Remember the following and try to follow this (here the “chain” is one LED or a few LINEARLY-connected LEDs): 1. EACH chain has its own current limiter (resistor or driver…) 2. Small chain up to 300mA? Just put in a resistor and that’s enough. 3. 3. Unstable voltage? Add a Voltage STABILIZER 4. 4. Current more than 300mA? Put a DRAWER (current regulator) on EVERY circuit, without a voltage regulator.

That’s the right way to do it, and most importantly, it will last a long time and shine brightly! Well, I hope that all of the above will save many people from mistakes and help save money and nerves.

Well, okay, a rowdy. There are a lot of nuances, and I’m already quite a big article I wrote. Perhaps the rest is in the comments. I’ll leave you now, always yours – IceBird Borisych.

PS: And yes, for the detractors. This post is not about wiring LEDs properly, it’s just a blunt advertisement for my personal blog. You are right as always and I am self-serving as always. Yep (just kidding) =)))

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