LEDs have long taken their place in our apartments. Without them, it is impossible to imagine electronic equipment, some modern toys for children. Whole ribbons, assembled from LEDs in a production environment, are decorated with pieces of furniture, automotive and motorcycles. They are lit in different colors, serve for a very long time, attract the attention of home craftsmen with their characteristics.
Every house has LEDs, but not everyone knows how to solder them correctly.
Many are interested in the question of the ability to independently solder circuits that include LEDs of different types. This scheme can be done by hand.
Recall a school course in physics
In order to solder the circuit, including LEDs, you need a soldering iron.
First you need to prepare a tester, a soldering iron and a calculator. One has to memorize such a simple thing: it is impossible to direct the beam going from the LED into the eyes of a person. And now it is time to recall a little physics:
- the letter “U” on the electrical circuit indicates the voltage measured in volts (V);
- the current is denoted by the letter "I", measured in amperes (A);
- electrical resistance of parts and conductors is denoted by the symbol "R" and is measured in ohms (Ohms);
- All these data are included in the formula characterizing Ohm's law: U = R * I;
- the letter "P" denotes power, measured in watts (W);
- power can be calculated by the formula: P = U * I.
How to turn on the LED?
LEDs are connected to the network with a voltage of 9 and 12 V.
Most often, the LEDs are included in the network with a voltage of 9 and 12 V. The most common devices are designed for a current consumption of 20 mA (0.02 A). Ideally, they are connected via current stabilizers, which cost significantly more LEDs. Red and yellow LEDs usually require a voltage of 2.0 V; white, green and blue - 3.0 V.
Practical task: there is a 12 V battery and several 2.0 V and 0.02 A LEDs. The simplest thing is to apply a voltage of 2.0 V to each diode. To do this, the extra 10 V must be extinguished using a resistor, which is often called resistance. The formula of Ohm's law: U = R * I. Find the resistance value: R = U / I. It turns out: R = 10.0 / 0.02 = 500 Ohms.
In order for the resistance not to burn out from excess heat, you need to calculate its power: P = 10.0 * 0.02 A = 0.2 W. It is better and more reliable to take the resistance of a somewhat larger capacity, but remember that with increasing power, its overall dimensions increase. Now you can connect the LED to the battery through a resistor, observing the polarity of the parts.Back to table of contents
How to solder LEDs?
To solder the LEDs you need a flux for aluminum.
Similarly, you can connect multiple diodes in series. It is recommended to select LEDs with the same parameters. Chains of LEDs of different colors can be installed and connected to a variety of systems. Easier to do it on an autotransport. You just need to remember that the voltage in the vehicle network is usually not 12, but 14-14.5 V. In addition, it is not always constant, there is also enough interference. To suppress interference, you must use a voltage regulator. You can assemble them on the basis of the K142EN8A, KREN8A microcircuits for the 9 V network. For 12 V, the K142EN8B and KREN8B are suitable.
For soldering a small soldering iron, the sting of which can heat up to 260 degrees, is suitable. The soldering process should not exceed 3-5 seconds for each point. Great help will medical tweezers. For soldering to be fast and of high quality, you need to use a special flux for aluminum, the usual tin-lead solder.
If you do not have experience in soldering, you should learn a little about this case. For trial exercises suitable wires of different sections. Insulation is removed from the ends of the wires. Fresh wires are usually not covered with oxides, you can immediately tin them. To do this, a small amount of solder is taken on the sting of a heated soldering iron, touches rosin and leads with a sting on the exposed parts of the wires. Solder spreads on the wire with a thin film.
If for some reason, tinning is difficult, you need to put the wire on an aspirin tablet and warm it for 3-5 seconds with a soldering iron. After this procedure, even the wire with traces of obvious oxidation is perfectly covered with tin. Exercise is useful until such time as the wires fail to get a quality and quickly tin. After that, you need to learn how to tinkle the stranded ends, which most often have to be unwound, to remove traces of oxidation from them, then wet them on an aspirin tablet.
Now soldering LEDs should occur easily and quickly.Back to table of contents
SMD LED soldering
SMD LEDs are powerless devices that are soldered to special pads.
SMD LEDs are powerless devices. They do not have traditional legs for soldering. They are soldered by special contact pads located on the instrument case. This can be done with a low-power soldering iron 10-12 watts. It is best to have for this work a special sting, which has a fork at the end. Another way out is to wind a copper wire with a diameter of 1 mm onto a standard sting. The ends of the wire will act as a fork.
If necessary, this nozzle can be removed from the sting, then to use again. The ends of the coiled wire are reduced and diluted depending on the size of the LED.Back to table of contents
What are diode strips?
Conventional LEDs have a glass flask of about 5 mm in diameter and legs-conclusions. A long leg means a positive pin, a short leg - a minus one. If you mix them up during the soldering process, nothing terrible will happen. Just the diode does not light up. Before soldering, all diodes are installed in their places, soldering points are processed with flux, ordinary tin and a soldering iron are soldered, the remains of the legs are biting off. It remains to carry out a test run of the system, connecting it to the battery. If everything works, you can install the LED system to the intended place.
The scheme of the cut LED strip.
For ease of use, LEDs are available as whole strips that can be cut and connected to each other. They are used for decorative lighting of various structures and lamps. You can cut the tape only in strictly designated places indicated on the tape. The distance between the cuts can be as follows:
- 2.5 cm;
- 5 cm;
- 10 cm
The soldering of the ribbon with LEDs is made by a regular 40-watt soldering iron. As a flux, a special flux in the form of a gel is often used. The ends of the wires must be well tinned together with the pads on the tape before soldering. For soldering use the usual solder PIC. There are special devices for connecting tape segments without soldering - connectors.
It remains to bring all the information in a single instruction, consisting of several points:
- For soldering, you need to prepare LEDs, solder PIC, flux, soldering iron, wire cutters, tweezers, sponge.
- The long lead of the LED means “+”, the short one means “-”.
- The LEDs are installed on pre-designed places on the circuit board, which can be both home-made and factory-made.
- Too long pins bite off with pliers.
- Wires are best used with a cross section of up to 0.75 mm.
- The soldering iron is turned on to heat up the network, its sting is cleaned with a damp sponge.
- The soldering point is heated by a soldering iron for 2-3 seconds.
- After a few seconds, the solder cools down, soldering is done.
Soldering iron is better to use a power of 40 watts. Flux is suitable brand LTI-120. It can be replaced with a solution of rosin in alcohol. An aspirin tablet often helps. Its only drawback is a very pungent and unpleasant smell. From devices it is nice to have a digital tester.
Set yourself a few LEDs of different colors in any device may well any home artist.
Especially difficult tools for performance of work is not required. It is necessary only to recall some knowledge from the field of physics and learn how to use a soldering iron. This will help in a few exercises on the parts and the wire. Very soon you will realize that soldering LEDs is easy!