I like that post as it teaches some of the circuit basic fundamentals and ideas, how to sense a ccfl actually working or not. Good work, thank you very much!
Great thank you for explaining i would like to know if is possible to take.the transformer off and get dont know. Maybe.same voltage like.input.for.a led but control on/off and dim as i guess dim/contrast is only voltage controll?
the first circuit is royer oscilator. good thing is with no load you can disconnect the resistors completely and increase the efficiency, but it will turn off when u increase the load, so the best solution is high resistance resistors-enough to start up and never let turn off and no big losses due to feedback coil current trough them
ENGLISH TEXT. How does an inverter work? Any picture displayed in an LCD technology device, requires an independent light, in order to be seen by the eye. Nowadays there are two different ways to produce that light. One is through cold cathode fluorescent lamps, and the other is based on leds (light emitting diodes) . Firstly, we are going to see how the cold cathode fluorescent lamps back light technology works. A high alternate current voltage, produced from a continuous current voltage is necessary. Because of that, the source that makes this work is called an INVERTER. At the same time, it is necessary a high frequency alternate voltage, to avoid interferences. And what are the necessary tools to get it? A high frequency oscilator circuit. Transistors, to make heavy or power work. And an elevator transformer in order to get the voltage up. Let us talk about the cold cathode fluorescent lamps. According to their size, they need more or less high voltages to operate. Their electrical resistence decreases as they heat. They eventually become less efficient and less illuminate. This can cause some problems: The high voltage is prone to cross the isolates, so there must be a shorts controller circuit . Since they conduct more as they heat, the voltage must decrease at some point, to avoid the lamp´s explosion. So, it is necessary to have circuits that contol the amount of voltage. And the inverter begins to operate in an intermitent way, or simply shuts down if it can not balance the brightness of a lamp assembly, since they gradually lose efficiency. It means that we have to add to the oscilator, the tranistors and the transformer, some circuits that control and watch over for a precise measure, so that nothing be left apart. Let´s begin with a simple circuit that is used in LG/ZENITH brand, for small TV screens (fifteen inches). The oscilator circuit consists of the following elements: The transformers. The capacitors. The transistors. This is the primary side of the transformer, and in parallel, there is a capacitor. These two elements easily oscillate or shake for a certain time, when a current passes through them or is suddenly discontinued. Where would the current come from? It turns out that the circuit is powered by a 9 volts source, more or less. But in order to produce current flow, we have to push one of these transistors to conduct. Let´s see that everyone of them has a six hundred and eighty ohms resistence at its base. Let´s assume that Q51 conducts, due to the excitement that the resistence 51 gives to the base; so this is the path of the main current. All this, causes the first half cycle of a sine wave in the transformer. To complete the cycle, it is necessary that the current walk the opposite way, driven by the other transistor, Q52. The oscilation of this circuit is fedback by a secondary winding which ensures that, in each half-cycle, only one transistor conduct while the other remains cut off. And all this work reflects on the elevator secondary winding, where the lamps are connected and, as a result begin to illuminate. Now: how or where the samples are taken, to make the necessary controls, so that the circuit work perfectly? This is accomplished by examining the ground return end of each lamp, since at this point the voltage is small and easy to handle, besides it´s a faithful sample of the entire process. The first thing is to make pass such sample by a rectifier circuit to convert it in DC. This is possible through two different circuits, one for intensity controls, and the other to detect if any lamp becomes open or disconnected. The current control circuit assumes the administration of the source that, we said, has around 9 volts, but can get down when it become necessary. For example, when the lamps are heated, because, as we know, they conduct more, and could burst. Let´s see how it is made: This is the source that regulates the nine volts of the inverter. The IC 51 is the TK eleven EIGHT forty L that, accompanied by the Q53 mosfet, the L52coil, the 55 and 56diodes, charge the C69 capacitor with a close to 9V voltage, that may rise or fall, according to the sample in DC taken from the lamps, and that comes in by its pin 1 EAIN (input of the error amplifier). This terminal inverts the information, which means that if the sample rises, the source will fall and viceversa. All this makes sense, since if the lamps conduct more, their internal resistence will be less. Therefore the sample will become higher and the source reaction will be geting down a bit of the voltage, in order to compensate.
TEXTO EN ESPAÑOL Cómo funciona una inversora Cualquier imagen reproducida en un aparato con tecnología lcd, requiere de una luz independiente para poder ser vista por el ojo. Actualmente existen en el mercado 2 maneras distintas de producir esa luz. Una es con lámparas de cátodo frío (ccfl) y la otra es con diodos emisores de luz (led). Vamos a ver primero cómo funciona la luz trasera o back light producida por lámparas. Es necesario un voltaje alto de corriente alterna, producido a partir de una tensión de corriente continua. Por esta razón a la fuente que hace este trabajo, se le llama inversora. También es preciso que la corriente alterna sea de alta frecuencia. De esta manera se evitan interferencias. Y cuáles son las herramientas para conseguirlo? Un circuito oscilador de alta frecuencia. Transistores para hacer el trabajo pesado o de potencia. Y un transformador elevador, para que suba el voltaje. Hablemos de las lámparas de cátodo frío: De acuerdo con su tamaño, necesitan voltajes más o menos altos para funcionar. Su resistencia eléctrica disminuye a medida que se calientan. Con el tiempo van perdiendo eficiencia y alumbran menos. Esto puede generar algunos problemas: El voltaje alto es propenso a cruzar los aislamientos, por tanto tiene que haber un circuito que controle cortos. Dado que conducen más a medida que se calientan, el voltaje debe bajar en cierto momento, para que la lámpara no se estalle. Entonces son necesarios circuitos que controlen la cantidad de voltaje. Y como van perdiendo eficiencia, pasa que la inversora, si no puede equilibrar el brillo de un conjunto de lámparas, comienza a trabajar de manera intermitente o simplemente se apaga. Lo anterior significa que al oscilador, los transistores y el transformador, debemos añadirles varios circuitos que controlen y vigilen para que no falte ni sobre nada. Veamos un circuito simple para comenzar: Es usado en la marca lg/zenith para televisores pequeños (15"). El circuito oscilador está compuesto por los siguientes elementos: Los transformadores Los condensadores Los transistores Este es el primario del transformador y en paralelo está puesto un condensador. Estos dos elementos oscilan o se sacuden fácilmente y por un tiempo determinado, cuando una corriente los atraviesa o se suspende súbitamente. De dónde vendría la corriente? Resulta que el circuito está alimentado por una fuente que tiene alrededor de 9V. Pero para que haya circulación de corriente, tenemos que hacer que uno de estos transistores conduzca. Miremos que cada uno de ellos tiene en su base una resistencia de 680Ω. Supongamos que conduce el Q51, gracias a la excitación que le brinda a la base la resistencia 51, y este es el camino de la corriente principal. ESTO provoca en el transformador el primer medio ciclo de una onda senoidal. Para completarlo, es necesario que la corriente recorra el camino inverso, impulsada por el otro transistor, Q52. La oscilación de este circuito es realimentada por un devanado secundario del transformador, que se encarga de que en cada hemiciclo sólo conduzca uno de los transistores, mientras el otro permanece cortado. Y todo este trabajo se refleja en el secundario elevador, donde están conectadas las lámparas que gracias a ello, empezarán a iluminar. Ahora: cómo o dónde se toman las muestras para hacer los controles necesarios, de modo que el circuito funcione perfectamente? Esto se lleva a cabo examinando el extremo de regreso a tierra de cada lámpara, ya que en este punto el voltaje es pequeño y fácil de manejar, además de ser una muestra fiel de todo el proceso. Lo primero es hacer pasar dicha muestra por un circuito rectificador para convertirla en DC. Esto se hace a través de 2 circuitos distintos, uno para controles de corriente y otro para detectar si alguna lámpara llega a abrirse o desconectarse. El circuito controlador de corriente se encarga de administrar el valor de la fuente, que dijimos está alrededor de los 9V, pero puede bajar cuando sea necesario. Por ejemplo cuando las lámparas se calientan, ya que, como sabemos conducen más y podrían estallarse. Veamos cómo lo hace: Esta es la fuente que regula los 9V de la inversora. El integrado 51 es el TK11840L que, en compañía del mosfet Q53, la bobina L52, los diodos 55 y 56, cargan el filtro C69 con un voltaje cercano a 9V, que puede subir o bajar, de acuerdo con la muestra en DC TOMADA de las lámparas y que entra por su terminal 1 EAIN (entrada del amplificador de error). Este terminal invierte la información. Esto quiere decir que si la muestra sube, la fuente bajará y viceversa, lo cual tiene lógica, puesto que si las lámparas conducen más, su resistencia interna será menor. Por consiguiente la muestra va a ser más alta y la reacción de la fuente será bajar un poco el voltaje, para compensar.
Heat is not (much) the factor that causes the change of resistance of a florescent lamp. It is ionizing the gas that decreases the resistance of the tube. The ballast, or driving circuit, Must deliver high enough voltage to start the lamp. Then the voltage must decrease to limit the current flowing thru plasma in the tube. For the curious; The old fashion ballast is really a weak transformer. It can only deliver enough high voltage to start the lamp. When the tube ionizes(lights) it's higher current draw pulls the voltage down to operating level.
Coil Smoke What is an inverter? Inverter is another name for Power Supply. It may raise or lower the voltage input. Because a transformer is used , Alternating Current must be fed to the transformer. Steady Direct Current will get you nothing out of a transformer. So if DC is used it must be " Oscillated " or chopped up into an alternating signal to power the primary of the transformer. Those two transistors and the transformer primary windings form an oscillator that that produces the desired varying voltage to the primary of the transformer. The number of secondary windings determines the AC voltage output. Less windings = less volts. For step up , more turns than the primary windings = more volts out. The name / word 'inverter' used to imply: A device for converting low voltage DC, like from a 12Volt battery to 120 Volts AC that can power home electric gadgets 'in the field'. Now manufactures are using " I N V E R T E R " because it sounds new, impressive and baffles customers into thinking they are dumber than the sales people. . Also there is a trend to using DC or different voltages in motors and devices traditionally just hooked to the AC line. The idea is better control circuits and less power consumption, WE HOPE ...
Hey there. Could give some advice? I have problem with my VAIO PCG-2J1L. I believe this is iverter board. Screen goes off after 2-3 minutes. Capacitor on this board looks OK, 4 secondary coils in 2 transformers show equal resistance. Do you have any ideas?
They sell a chiller spray that is used to cool suspect components. The theory being, some components fail as they warm up and may start working when cooled by the spray. It's a very old school trick that can pinpoint bad parts.
Coil Smoke Thx) This sounds very interesting and possibly will work but some SMDs on this board are very tiny) Another problem is to get this cooling spray here in Russia) But I will take a look in local shops.
ANTONIO ROJAS El capacitor forma "pareja" con la bobina y a eso se le llama un Circuito Resonante, de modo que entre ambos fijan la frecuencia de oscilación del circuito. Si falta el capacitor, no hay límite de corriente a través del transistor de turno y la fuente se pone en corto a través de este, deteriorándolo. Algo similar ocurre cuando el capacitor se pone en corto, y sucede.
Marius Beets It is a very difficult subject.It wont make much different should it be in English. you wont understand much anyway neither I. His accent is OK.
I like that post as it teaches some of the circuit basic fundamentals and ideas, how to sense a ccfl actually working or not. Good work, thank you very much!
Great thank you for explaining i would like to know if is possible to take.the transformer off and get dont know. Maybe.same voltage like.input.for.a led but control on/off and dim as i guess dim/contrast is only voltage controll?
Muchisimas gracias por la aclaracion
the first circuit is royer oscilator. good thing is with no load you can disconnect the resistors completely and increase the efficiency, but it will turn off when u increase the load, so the best solution is high resistance resistors-enough to start up and never let turn off and no big losses due to feedback coil current trough them
ENGLISH TEXT.
How does an inverter work?
Any picture displayed in an LCD technology device, requires an independent light, in order to be seen by the eye.
Nowadays there are two different ways to produce that light. One is through cold cathode fluorescent lamps, and the other is based on leds (light emitting diodes) .
Firstly, we are going to see how the cold cathode fluorescent lamps back light technology works.
A high alternate current voltage, produced from a continuous current voltage is necessary.
Because of that, the source that makes this work is called an INVERTER.
At the same time, it is necessary a high frequency alternate voltage, to avoid interferences.
And what are the necessary tools to get it?
A high frequency oscilator circuit.
Transistors, to make heavy or power work.
And an elevator transformer in order to get the voltage up.
Let us talk about the cold cathode fluorescent lamps.
According to their size, they need more or less high voltages to operate.
Their electrical resistence decreases as they heat.
They eventually become less efficient and less illuminate.
This can cause some problems:
The high voltage is prone to cross the isolates, so there must be a shorts controller circuit .
Since they conduct more as they heat, the voltage must decrease at some point, to avoid the lamp´s explosion. So, it is necessary to have circuits that contol the amount of voltage.
And the inverter begins to operate in an intermitent way, or simply shuts down if it can not balance the brightness of a lamp assembly, since they gradually lose efficiency.
It means that we have to add to the oscilator, the tranistors and the transformer, some circuits that control and watch over for a precise measure, so that nothing be left apart.
Let´s begin with a simple circuit that is used in LG/ZENITH brand, for small TV screens (fifteen inches). The oscilator circuit consists of the following elements:
The transformers. The capacitors. The transistors.
This is the primary side of the transformer, and in parallel, there is a capacitor. These two elements easily oscillate or shake for a certain time, when a current passes through them or is suddenly discontinued.
Where would the current come from?
It turns out that the circuit is powered by a 9 volts source, more or less. But in order to produce current flow, we have to push one of these transistors to conduct.
Let´s see that everyone of them has a six hundred and eighty ohms resistence at its base. Let´s assume that Q51 conducts, due to the excitement that the resistence 51 gives to the base; so this is the path of the main current.
All this, causes the first half cycle of a sine wave in the transformer. To complete the cycle, it is necessary that the current walk the opposite way, driven by the other transistor, Q52.
The oscilation of this circuit is fedback by a secondary winding which ensures that, in each half-cycle, only one transistor conduct while the other remains cut off.
And all this work reflects on the elevator secondary winding, where the lamps are connected and, as a result begin to illuminate.
Now: how or where the samples are taken, to make the necessary controls, so that the circuit work perfectly?
This is accomplished by examining the ground return end of each lamp, since at this point the voltage is small and easy to handle, besides it´s a faithful sample of the entire process.
The first thing is to make pass such sample by a rectifier circuit to convert it in DC. This is possible through two different circuits, one for intensity controls, and the other to detect if any lamp becomes open or disconnected.
The current control circuit assumes the administration of the source that, we said, has around 9 volts, but can get down when it become necessary. For example, when the lamps are heated, because, as we know, they conduct more, and could burst. Let´s see how it is made:
This is the source that regulates the nine volts of the inverter. The IC 51 is the TK eleven EIGHT forty L that, accompanied by the Q53 mosfet, the L52coil, the 55 and 56diodes, charge the C69 capacitor with a close to 9V voltage, that may rise or fall, according to the sample in DC taken from the lamps, and that comes in by its pin 1 EAIN (input of the error amplifier). This terminal inverts the information, which means that if the sample rises, the source will fall and viceversa. All this makes sense, since if the lamps conduct more, their internal resistence will be less. Therefore the sample will become higher and the source reaction will be geting down a bit of the voltage, in order to compensate.
Estoy deseando verlo. Gracias.
Saludos.
Loved it !!!! ... even though it's hard to understand .. more vids, pls :)
Thank you
TEXTO EN ESPAÑOL
Cómo funciona una inversora
Cualquier imagen reproducida en un aparato con tecnología lcd, requiere de una luz independiente para poder ser vista por el ojo.
Actualmente existen en el mercado 2 maneras distintas de producir esa luz. Una es con lámparas de cátodo frío (ccfl) y la otra es con diodos emisores de luz (led).
Vamos a ver primero cómo funciona la luz trasera o back light producida por lámparas.
Es necesario un voltaje alto de corriente alterna, producido a partir de una tensión de corriente continua. Por esta razón a la fuente que hace este trabajo, se le llama inversora.
También es preciso que la corriente alterna sea de alta frecuencia. De esta manera se evitan interferencias.
Y cuáles son las herramientas para conseguirlo?
Un circuito oscilador de alta frecuencia.
Transistores para hacer el trabajo pesado o de potencia.
Y un transformador elevador, para que suba el voltaje.
Hablemos de las lámparas de cátodo frío:
De acuerdo con su tamaño, necesitan voltajes más o menos altos para funcionar.
Su resistencia eléctrica disminuye a medida que se calientan.
Con el tiempo van perdiendo eficiencia y alumbran menos.
Esto puede generar algunos problemas:
El voltaje alto es propenso a cruzar los aislamientos, por tanto tiene que haber un circuito que controle cortos.
Dado que conducen más a medida que se calientan, el voltaje debe bajar en cierto momento, para que la lámpara no se estalle. Entonces son necesarios circuitos que controlen la cantidad de voltaje.
Y como van perdiendo eficiencia, pasa que la inversora, si no puede equilibrar el brillo de un conjunto de lámparas, comienza a trabajar de manera intermitente o simplemente se apaga.
Lo anterior significa que al oscilador, los transistores y el transformador, debemos añadirles varios circuitos que controlen y vigilen para que no falte ni sobre nada.
Veamos un circuito simple para comenzar:
Es usado en la marca lg/zenith para televisores pequeños (15"). El circuito oscilador está compuesto por los siguientes elementos:
Los transformadores
Los condensadores
Los transistores
Este es el primario del transformador y en paralelo está puesto un condensador. Estos dos elementos oscilan o se sacuden fácilmente y por un tiempo determinado, cuando una corriente los atraviesa o se suspende súbitamente.
De dónde vendría la corriente?
Resulta que el circuito está alimentado por una fuente que tiene alrededor de 9V. Pero para que haya circulación de corriente, tenemos que hacer que uno de estos transistores conduzca. Miremos que cada uno de ellos tiene en su base una resistencia de 680Ω. Supongamos que conduce el Q51, gracias a la excitación que le brinda a la base la resistencia 51, y este es el camino de la corriente principal.
ESTO provoca en el transformador el primer medio ciclo de una onda senoidal. Para completarlo, es necesario que la corriente recorra el camino inverso, impulsada por el otro transistor, Q52.
La oscilación de este circuito es realimentada por un devanado secundario del transformador, que se encarga de que en cada hemiciclo sólo conduzca uno de los transistores, mientras el otro permanece cortado.
Y todo este trabajo se refleja en el secundario elevador, donde están conectadas las lámparas que gracias a ello, empezarán a iluminar.
Ahora: cómo o dónde se toman las muestras para hacer los controles necesarios, de modo que el circuito funcione perfectamente?
Esto se lleva a cabo examinando el extremo de regreso a tierra de cada lámpara, ya que en este punto el voltaje es pequeño y fácil de manejar, además de ser una muestra fiel de todo el proceso.
Lo primero es hacer pasar dicha muestra por un circuito rectificador para convertirla en DC. Esto se hace a través de 2 circuitos distintos, uno para controles de corriente y otro para detectar si alguna lámpara llega a abrirse o desconectarse.
El circuito controlador de corriente se encarga de administrar el valor de la fuente, que dijimos está alrededor de los 9V, pero puede bajar cuando sea necesario. Por ejemplo cuando las lámparas se calientan, ya que, como sabemos conducen más y podrían estallarse. Veamos cómo lo hace:
Esta es la fuente que regula los 9V de la inversora. El integrado 51 es el TK11840L que, en compañía del mosfet Q53, la bobina L52, los diodos 55 y 56, cargan el filtro C69 con un voltaje cercano a 9V, que puede subir o bajar, de acuerdo con la muestra en DC TOMADA de las lámparas y que entra por su terminal 1 EAIN (entrada del amplificador de error). Este terminal invierte la información. Esto quiere decir que si la muestra sube, la fuente bajará y viceversa, lo cual tiene lógica, puesto que si las lámparas conducen más, su resistencia interna será menor. Por consiguiente la muestra va a ser más alta y la reacción de la fuente será bajar un poco el voltaje, para compensar.
Excelente!
Thanks
very good
good
Heat is not (much) the factor that causes the change of resistance of a florescent lamp. It is ionizing the gas that decreases the resistance of the tube. The ballast, or driving circuit, Must deliver high enough voltage to start the lamp. Then the voltage must decrease to limit the current flowing thru plasma in the tube. For the curious; The old fashion ballast is really a weak transformer. It can only deliver enough high voltage to start the lamp. When the tube ionizes(lights) it's higher current draw pulls the voltage down to operating level.
Coil Smoke What is an inverter? Inverter is another name for Power Supply. It may raise or lower the voltage input. Because a transformer is used , Alternating Current must be fed to the transformer. Steady Direct Current will get you nothing out of a transformer. So if DC is used it must be " Oscillated " or chopped up into an alternating signal to power the primary of the transformer. Those two transistors and the transformer primary windings form an oscillator that that produces the desired varying voltage to the primary of the transformer. The number of secondary windings determines the AC voltage output. Less windings = less volts. For step up , more turns than the primary windings = more volts out.
The name / word 'inverter' used to imply: A device for converting low voltage DC, like from a 12Volt battery to 120 Volts AC that can power home electric gadgets 'in the field'. Now manufactures are using " I N V E R T E R " because it sounds new, impressive and baffles customers into thinking they are dumber than the sales people. . Also there is a trend to using DC or different voltages in motors and devices traditionally just hooked to the AC line. The idea is better control circuits and less power consumption, WE HOPE ...
Coil Smoke excellent contribution . Thank you
Hey there. Could give some advice? I have problem with my VAIO PCG-2J1L. I believe this is iverter board. Screen goes off after 2-3 minutes. Capacitor on this board looks OK, 4 secondary coils in 2 transformers show equal resistance. Do you have any ideas?
They sell a chiller spray that is used to cool suspect components. The theory being, some components fail as they warm up and may start working when cooled by the spray. It's a very old school trick that can pinpoint bad parts.
Coil Smoke Thx) This sounds very interesting and possibly will work but some SMDs on this board are very tiny) Another problem is to get this cooling spray here in Russia) But I will take a look in local shops.
veri naies
que funcion hace el capacitor y que pasaria si no estuviera
muchas gracias
ANTONIO ROJAS El capacitor forma "pareja" con la bobina y a eso se le llama un Circuito Resonante, de modo que entre ambos fijan la frecuencia de oscilación del circuito.
Si falta el capacitor, no hay límite de corriente a través del transistor de turno y la fuente se pone en corto a través de este, deteriorándolo. Algo similar ocurre cuando el capacitor se pone en corto, y sucede.
sir what is the purpose of inductance (L) in the circuit
could you give replay to me
DHARAVATH SUMAN I hope you read the "English Text"
Help help help
I have this SINE WAVE model ps-T12.5kva can some one show me how to conect it to batery and electricity
Thankz
Best regard kossi kini
Hola, Fredy......muy bueno el video, pero..... de pronto podrías conseguirte un angloparlante nativo para narrarlo? Me costó MUCHO trabajo entenderte.
Hola Nicolas, el video está en español. Cómo funciona un circuito inversor en LCD
Deberías colocar subtítulos al español
hola q tal don fredy
Hola Emiro. Mucho gusto
Can you explain it in English please...
This guy sounds like some character from video game)
+Marius Beets Dat racism tho
He sounds like c3p0
Marius Beets hello
Marius Beets It is a very difficult subject.It wont make much different should it be in English. you wont understand much anyway neither I. His accent is OK.
I ned biggener class
hi
Mast bolna kya....
extremely difficult accent to understand
Learning english
hi