Construir
Comprar iluminária, fluroscentes, balastro, economizadoras e leds
- nunocapucho1981
- 19 fevereiro 2015
Se quer um conselho, compre por cá e com garantia. Nao compre chinesisses. Atenção que uma coisa é comprar material feito na China e outra coisa é comprar material chinês.
Isso nem devia aquecer.
Se quiser preços envie mp.Comprei duas lâmpadas de 60cm no lidl. Ontem fui para montar na cozinha dos meus pais, e rapidamente percebi que não dava para plug anda play, uma vez as armaduras com 2x 60 partilham quase sempre o mesmo balastro, ou seja configuração tandem
No meu caso fiz modificações ao circuito original, sendo que anulei completamente o balastro e liguei ambas em paralelo directamente.
Mas mantive os arnacadores dummy, no fundo aquilo e uma resistência para ai de 1 ohm , ser vê de fusível
Isto assim ficou porreiro pois as duas lâmpadas são agora independentes, o que. Não acontecia anteriormentebom dia, queria meter luz indireta na sala. Tenho ideia que o que dá boa luz são as comuns flourescentes T8. Há fitas de led com lumens equivalentes? preços?As fitas de LED não são, na sua maioria, nada de especial. Por que não substituir por T8 LED?supostamente as lampadas led nao deveriam ter cintilação, mas na realidade têm que ter, pois quando se aponta a camara fotografica (ou do telemovel) , sente-se o cintilar da lampada...
Ora experimentem a fotografar uma lampada led de 220v de pertoEntretanto tenho estado atento, e constato que praticamente todas as lampadas LED têm cintilação , aparentemente 50hz
talvez as fontes que vêm nos casquilhos não tenham boa qualidade de filtragemNinguem me tem levado a sério nesta historia da cintilação dos LED´s, mas deixo aqui alguns sites que retratam esta situação , transcrevo ainda alguns excertos (em ingles)
http://www.ledbenchmark.com/faq/LED-Flicker-Measurement.html
AC lighting including incandescent, CFL and LED types generally exhibit varying degrees of flicker; usually at double the line frequency (100Hz flicker for a 50Hz mains frequency or 120Hz for a 60Hz mains frequency). While flicker above 75 Hz is not noticeable to most individuals, the perceptibility of flicker is not just a function of frequency but also the relative intensity of the peaks and troughs of the light output waveform (modulation) and the shape of the waveform, which describes the duration of varying light levels over time within each cycle (duty cycle).
The degree of modulation, reflected in the percent flicker and flicker index metrics described below, has a substantial effect on the maximum frequency at which flicker is detectable, called the flicker fusion threshold. Deeper modulation and longer instances of low light intensity, corresponding to a higher percent flicker and flicker index respectively, increases the frequency threshold at which flicker can have an effect, particularly on photo-sensitive individuals. The consequence of this being that flicker can remain a potential health concern even at frequencies above 75 Hz.
It is important to note that while some LED lights did produce greater degrees of non-visible flicker than conventional light sources in terms of the metrics used, it was by no means a characteristic of all LED lighting and tended to occur in lower quality, cheaper products.
LEDs will emit steady light if given steady current. The question then becomes what kind of current waveform LEDs are driven with in a light assembly.
The exact answer depends on the circuit in the light. LEDs run on just a few volts. The much high line voltage has to be converted to the lower LED voltage somehow. Most likely, this will include the cheapest, dumbest, and most stripped down switching power supply possible.
I see other answers mention a transformer, but I think that is quite unlikely. There is no need for isolation in a sealed unit with no external connections other than the power line. Even if there is a transformer, it's not going to be fed directly from the line frequency. The extra savings in cost and size of a transformer that works at 10s to 100s of kHz far outweighs the cost of the components to produce that frequency.
Most likely, there is a full wave bridge to rectify the AC line voltage directly. That will then be chopped thru a inductor to drive the LEDs. Depending on how cheap the lamp is, it might chop at a fixed duty cycle, which would make the LED brightness vary with power voltage. Even a little current feedback would keep the LED current reasonably constant over most of the line cycle, perhaps dipping only briefly at the power line zero crossings. A small cap would reduce that, but caps cost money and take space, so may not be included.
LED lamps are made in large volumes, so serious manufacturers probably develop custom ICs just for this purpose. In such a case I'd expect at least some attempt at regulation, so the LED brightness will be largely constant, perhaps with short dips at the power line zero crossings.
However, all this is speculation. Why not just look? Put the lamp at the end of a extension cord and swing it around in a otherwise darkened room. Whether it flickers or not will be immediately obvious.
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E tambem os led´s dos ecrans cintilam. A asus tem uns novos que usam como argumento de venda a baixa cintilacao :
http://www.asus.com/Microsite/2015/display/eye_care_technology/-
Pedro Barradas
- 12 fevereiro 2016
Isso é bem verdade....
Reparem nas imagens slow motion de videos de viaturas dotadas de farois led... pisca- pisca-pisca....
Tenho um monitor LED da BENQ, tem a tecnologia eye care e diminuição da Blue light emission ( e um monitor de gama profissional, para CAD/CAM e design gráfico). O que é certo é se tirar uma foto não noto o refresh que notava no anterior monitor.... o mesmo se passa no Portátil ASUS.Ola pedro barradas
A asus anda a fazer muita publicidade a volta da tecnologia eye care: http://www.asus.com/Microsite/2015/display/eye_care_technology/
Quanto a lampadas led, estou arrependido de ter colocado spots led do lidl na minha sala e corredor
Dao boa luz, mas piscam que se fartam .... a ponte rectificadora deve ser o mais minimal possivel
Talvez os spots led de 12v DC nao pisquem tanto
No entao os LED de corrente continua tambem têm os seus defeitos:
Adaptei um projector destes de aluminio de 10W , comprado no ebay, a um booster de 12v, e quando ligo o projector o radio FM fica completamente inaudivel com interferencias
Afinal nao sou só eu a imaginar que a iluminacao LED interefere com os radios:
The problem is probably getting worse for another reason. In order to prolong the life of the LED, they need to be run off a constant current source, which is provided by a switched mode electronic power supply. The frequencies used in these power supplies is getting higher, producing interference in the range 30 - 300Mhz. DAB in the UK is roughly in the 210-230 Mhz band. Easy to see why the problem happens.
https://conversation.which.co.uk/technology/your-view-led-bulb-interference-dab-radios/
https://www.avforums.com/threads/led-lights-interferes-with-dab-signal.1330696/0.0262 seg. NEW
