Dimmable Lighting Buzzing

[ban-all-sheds]

I have had fitted 13 Downlights to my lounge

Was that because your lounge is the size of a tennis court, or because you chose lights which are so poor at doing the job of lighting up a room that you needed a swathe of them?

and all fitted with 5W LED Dimmable Lamps from LEDHut. Since I have over 10 LEDs I fitted the Varilight V-Pro 300W dimmer switch. TRouble is that the lamps buzz unless you are at full light. I have tried the 3 different modes on the V-Pro and although Mode 3 seems best there is still a buzz. I am tempted to return the bulbs to LED Hut but dont know what to replace with. Any thoughts?

If the people you bought them from say they are dimmable, do they specify any particular dimmers, or type of dimmer?

 

[nellymcl]

Was that because your lounge is the size of a tennis court, or because you chose lights which are so poor at doing the job of lighting up a room that you needed a swathe of them?

Thanks for your helpful comment! Actually at 7m long and 4 m wide and a height of 2.4m I used the half the height of the ceiling for the spacing of 1.2m. If you do the maths then 7/1.2 gives you 5.8 and 4/1.2 gives you 3.3. Multiplying them together gives you more than the 13 I have. Also taking into account where my joists run and a 38° angle on the lamps my 13 does the job just fine. Being warm white on 2700 also means they are not floodlights. I might have been better saying I lived on a tennis court!!

If the people you bought them from say they are dimmable, do they specify any particular dimmers, or type of dimmer?

The dimmer I bought is the one specified.

Cheers

 

[ban-all-sheds]

Multiplying them together gives you more than the 13 I have.

Indeed.

And using lights fit for purpose gives you a lot fewer.

 

[aptsys]

Since LED hut recommend the varilight, it looks like I will be returning the lamps to LED hut and going for another brand.

LED hut lamps are generic Chinese lamps that they've had branded. They're certainly not good quality.

Go for Philips or Osram if you can, but the Enlite ones are quite good too.

 

[bernardgreen]

Bottom line is that any equipment used for lighting ( including dimmers, drivers, transformers ( all types ) etc etc ) should not have any components that can vibrate enough to create any sound that can be heard.

 

[aptsys]

Bottom line is that any equipment used for lighting ( including dimmers, drivers, transformers ( all types ) etc etc ) should not have any components that can vibrate enough to create any sound that can be heard.

Unfortunately it's quite difficult to avoid when the supply frequency and it's harmonics are in the audible frequency range. There's quite a lot of microphonic passive components which are difficult to design out without passing the cost onto the customer.

 

[bernardgreen]

There's quite a lot of microphonic passive components which are difficult to design out without passing the cost onto the customer.

Sorry 50 years experience tells me that is not acceptable for any decent manufacturer. Though maybe the dropping of standards and Joe Public accepting cheap and poor quality goods has dealt a death blow to quality manufacturing.

Transformers can be "silenced" by dipping them in hot molten wax until the air bubbles stop.
If a capacitor is making a noise then it will self destruct as vibration shatters the insulation between plates.

 

[aptsys]

Sorry 50 years experience tells me that is not acceptable for any decent manufacturer. Though maybe the dropping of standards and Joe Public accepting cheap and poor quality goods has dealt a death blow to quality manufacturing.

Transformers can be "silenced" by dipping them in hot molten wax until the air bubbles stop.
If a capacitor is making a noise then it will self destruct as vibration shatters the insulation between plates.

Even potted inductors can buzz - it depends on the core construction as well. Ceramic capacitors are extremely microphonic, but will not suffer damage and essentially represent a piezo transducer.

The main problem is the dimmer does not know the properties of the load. You can only soften the high frequency edges of the waveform with inductors and inductors inherently buzz at mains frequency as they all suffer hysteresis losses. You can reduce the effect with a snubber across the switching element, but plastic capacitors are expensive so everyone fits ceramics to keep costs down because no one wants to pay lots of money for a dimmer...

LEDs should be dimmed with a control input to the constant current driver. Chopping the mains up is always going to cause issues with noise.

 

[ban-all-sheds]

Though maybe the dropping of standards and Joe Public accepting cheap and poor quality goods has dealt a death blow to quality manufacturing.

everyone fits ceramics to keep costs down because no one wants to pay lots of money for a dimmer....

There is hardly anything in the world that someone cannot make a little worse and sell a little cheaper, and the people who consider price alone are that person's lawful prey.

 

[bernardgreen]

Ceramic capacitors are extremely microphonic, but will not suffer damage and essentially represent a piezo transducer.

Please tell me who supplies your ceramics so I can avoid that supplier.

 

[aptsys]

Please tell me who supplies your ceramics so I can avoid that supplier.

It's a characteristic of every ceramic cap.

 

[bernardgreen]

Along with the noise reduction of electronic devices, the "acoustic noise" caused by the vibration of capacitors, which was not conventionally noticeable, has become a design issue in the power circuits of various applications, such as laptop computers, mobile phones, DSC, etc. (Location shown in Figure 1.)

http://www.murata.com/en-eu/products/capacitor/mlcc/solution/naki

I live and learn but then as said it has become a design issue with power circuits and almost entirely where the SMD ( Surface Mounted Device ) capacitor is using the PCB as a sounding board.