I want to implement a lighting system and control the light intensity of each LED lamp. I thought about using an LED light with some communication protocol, but it seems that it is very expensive so I decided to design a circuit with a TRIAC (you know the classic dimmer) to be able to control an LED tube or an LED reflector, but I don't know if with that I can get what I want, since I understand that LED lights have an internal driver and I don't know if the circuit that I intend to make will work. What would be the most efficient way to control the intensity of an LED tube or an LED reflector?
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2\$\begingroup\$ We need some help. Leds operate on DC. Using a triac with DC works sorta. Once triggered it will not turn off until the current falls below the triac holding current. By far the best way is to use PWM (Pulse Width Modulation). Leds are current devices, not voltage. Without knowing more about your application I cannot give you much more. Please state the voltages involved, LED tube, current, etc. How many lamps are involved, what protocol are you looking at. Post a schematic if you have one. \$\endgroup\$– GilFeb 14 at 2:08
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2\$\begingroup\$ The way you control the brightness depends on how the power supply works. Does the manual for the device say that it is dimmable? If not, do you know what voltage the power supply provides? Depending on the details it may be easy or you may need to replace the integrated drivers. \$\endgroup\$– user1850479Feb 14 at 2:36
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2 Answers
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Identify the LED tube, manufacturer, part number.
I bought some that had an internal driver where the 'dim' pin was unused. I provided it with the requisite voltage, and the tube dimmed. Of course I had to dismantle the tube, and google for info on the IC used within it.
The chance of being able to dim a random LED tube from the outside is next to zero, unless the tube advertises that it uses a published protocol for communicating with it.
If the tube is the type where you can plug it into an existing fixture, that means it has a wide range input voltage capability to cope with the various different components it might be supplied from, guarranteed to prevent you being able to control it simply by altering or chopping the supply.
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\$\begingroup\$ I found the same information, I must use a LED tube that has a specific connection to be able to control the dimming, otherwise it cannot be controlled. \$\endgroup\$– WalterPHFeb 15 at 16:05
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\$\begingroup\$ @WalteRPH many LED lights that are designed to plug into the wall are also designed to work with triac dimmers. They should be advertised as dimmable. But you didn't really say what kind of LED tubes you're talking about. \$\endgroup\$ Feb 15 at 17:43
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Short answer - you can control the brightness a very little only. The reason is that almost all LED bulbs which work on the mains have a circuit inside which convert the mains into a more "user friendly" voltage/ current for the LEDS. Changing the voltage by using dimmer tactics will more likely cause these circuits to fail rather than have any useful impact on the brightness.
Having said that, there ARE a few LED stacked "lights" which use a large number of LEDS in series powered directly from mains with just a series resistor. These CAN be dimmed.
However - you have to know which is which before committing.
