Among the majority of lighting elements, 12 Volt (LED) LEDs were especially popular. Small bulbs consume a minimum of electricity. At the same time they give a wide range of lighting colors and serve up to 40,000 hours.
Features of connecting LED bulbs
The scope of LEDs is quite wide - from the production of TV equipment to the backlights in residential, commercial premises. However, not every master knows how to connect small lamps. All distinguish three LED mounting methods:
- consistent;
- parallel;
- combined.
In addition, the LED lamp can also be connected to a 220 Volt network. In any case, the connection is made only to DC sources.
Connection Principles
To install LED lamps, there are several important principles that should be followed:
- It is important to observe the polarity when connecting the LED. Otherwise, it will fail faster or will not glow at all.
- The location of the anode and cathode is indicated on the lamp base in the form of notches, green dots.
- It is forbidden to install lamps of different colors in a single line and on a single resistor. This affects their performance and, in principle, glow.
- Polarity information can be found in the LED technical documentation.
For every 12 V, a maximum of 6 LEDs can be connected.
Types of Power Supplies
Each 12V LED should only be connected to a power source with the same voltage. Moreover, the IP must have a stable output current. It is easiest and most desirable to connect LEDs to such 12 V power supplies:
- Transformerless BP (power supplies). They have an output resistor and a quenching capacitor. But in such power supplies there is no stabilizing protection. This greatly affects the duration of the bulbs during power surges.
- Car battery. If you connect the LED to the battery, you need to choose a resistor in terms of power and resistance.
- Unstabilized BP. Their main components are a capacitor, a rectifier and a step-down transformer. Such power supplies are relevant for objects with a stable voltage.
- Switching power supplies. As an example, you can take a computer power supply. If the user will not be disturbed by the noise of coolers, you can use it
The cost of a new 12 volt power supply depends on the version (case availability or absence) and on the power calculated in watts.
How to determine the polarity of the LED
All 12 volt LEDs (white, red, blue, and other colors) have an anode and a cathode (polarities). They must be taken into account when connecting the LED. You can determine the polarity in one of the ways:
- By design. One of the legs on the bulb base is always several mm longer. This is the anode. It is marked with a “+” or a green dot.
- On the bowl inside the flask. If you look closely, you can see two crystals on it. The larger one indicates the cathode. The smaller one is the anode.
- Using a multimeter. To do this, the device must be set to "Call" mode. Then the probes of the apparatus are brought to the cathode and anode. To the first - black, to the second - red. When positioned correctly, the light should be on. If this does not happen, then the master incorrectly defined “+” and “-”. It is necessary to change the position of the probes.If this does not help, the LED is simply faulty.
Sometimes masters determine the polarity of the LED using a battery. But it is painstaking. It is better to use the above methods.
Ways to connect LEDs to 12 volt IP
To connect the LED to 12 volts, if its voltage is only 3V, you will have to compensate for excesses of 9 volts through a resistor or a zener diode (which is inefficient), or connect the ice lamps in series of three at a time.
Five red and yellow LEDs can be connected at once, since the voltage drop is below 2.2 volts.
Before calculating the resistor, you need to find out the operating voltage of each bulb. It is measured independently or information is found out from the technical documentation.
LEDs on 12V connect only through the stabilizer. If we are talking about connecting a tape of lamps in an IP, it is important to know that they have a limiting resistor designed for each group of several LEDs.
Serial connection
If the master connects the 12-volt LED in a serial circuit, the lamps are assembled in a chain. In this case, the cathode of each previous element is soldered to the anode of each next.
With this assembly scheme, a current of 20 mA passes through all the bulbs. The voltage level here also consists of the sum of the volt drop on each of them. Thus, it is forbidden to connect an arbitrary number of bulbs in one circuit.
If you need to connect a large number of LED lamps in series, you need to take a power source with large indicators for voltage and power.
The disadvantages of serial connection include:
- Failure of the entire light chain when a single element breaks.
- The need to purchase a more powerful IP when installing a large number of lamps.
As an example of a serial connection, you can consider a standard Christmas tree garland. If one element breaks down, it all stops working. Therefore, you need to find the detached contact and solder it again.
Action algorithm
To connect the LED to 12V DC, you need to learn the basic algorithm of actions:
- Determine the type of power supply, find out its output voltage and overall performance.
- Identify the rated current LED, power consumption and voltage.
- They determine the ability to connect LEDs to the power supply according to the available parameters.
- Connect and solder the bulbs in accordance with the polarity. The resistor is placed on any part of the chain.
Contacts after completion of work are carefully isolated.
How many LEDs can be connected to 12 volts
To find out how many LEDs can be connected to 12 V, you need to divide Upit by Upad. Or it is allowed to proceed from an average value of 2 Volts for each bulb. Thus, for every 12 V it is allowed to mount no more than 6 LEDs. If you take into account that some part of the voltage (approximately 2 V) must go to the quenching resistor, the number of diodes will decrease by one.
The LED voltage is not always equal to 2 V. In addition, when connecting and connecting the LED, the shade of the glow of the bulb and its brightness should be taken into account. To determine the exact number of lamps per twelve volt PSU, you can use a special program.
Common mistakes
Often, wizards make mistakes when installing LEDs. The most relevant of them:
- Connecting bulbs directly without a resistor. In this case, the diodes simply burn out.
- Perform parallel connection with a single resistor. Such an error threatens the gradual failure of all bulbs. After all, each has its own working current.
- Incorrectly selected resistor.In this case, too much current passes through the bulbs, which again leads to their burning. If the resistance is large, the elements will not shine brightly enough.
- Performing a series connection with different consumption currents. Two options are possible here - the lamps will glow with different intensities of brightness, or those that are designed for less current will burn out.
- Connecting ice lamps to AC 220 without using a diode or other protective components. The bulb receives a voltage of 315 V, which instantly leads to its combustion.
If you take these errors into account and connect the LEDs correctly, the decorative backlight that the master decided to build at home will work for a long time and properly.
