LED Dimmer

[Ioannis]

In the market there are a lot of LED lamps that advertise that they are Dimmer compatible.

Testing few of these LED lamps has proven that they are not so compatible.

Maybe because they have a specific voltage range (80-260 volts AC) that they operate besides other reasons.

My client asks for a dimmer design with a controller so that he can set the lower and higher limits, memory and operation in general. That is the easy part.

The difficult is power part of the circuit. After a lot of search I think that the best is to use trailing edge control with bridge and transistors. If anyone has experience in this or has any other working idea, please reply.

Thanks,
Ioannis

[Charlie]

LEDs are low voltage devices - on the order of 3 V. Any LED bulb that runs off of 80-260 Volts has internal circuitry to convert to a lower voltage. Unfortunately, there is no standard method to do the conversion, which means there is no standard method to dim them. You might find the perfect method for your sample bulbs, but those of another manufacturer won't work at all with your circuit. Or won't dim properly, or overheat and catch fire. If your customer wants to dim specific models from specific vendors, you have a chance, otherwise you'll have to wait for a standard to emerge.

[Ioannis]

Thanks Charlie. The dimmer is not going to control non dimmable led lamps. Only those that are specified as this.

But unfortunately even this has not really consistent results.

I have disassembled a Legrand dimmer that is trailing edge one. Inside is a factory in the size of a really small form! Three pcbs and two power transistor with a bridge among others. Amazing what they put inside this little box.

Have not found more details or a working circuit on this kind of application.

Ioannis

[Charlie]

Sorry, in my haste to explain why I added confusion.
Just because it says dimmable on the package does not mean it is dimmable by conventional dimmers or methods. Some are targeted at trailing edge, some leading edge, some lower the voltage, some require you buy their proprietary dimmer, and so on. The reasons are in my earlier post. To create a good dimmer you will need to choose a specific bulb, understand how it does the conversion to voltages the LED can use, then choose a method compatible with that converter design.

[Ioannis]

Thanks Charlie for the info.

Ioannis