LED bulb effectiveness

[rafis]

I noticed that my home bulbs consume 9W power, while they are 3W. I have about 20 of them all over my rooms. Is there any way to increase effectiveness (by putting transformer, for example)? This is personal hobby like effort, so there is no aim to make it cheap or compact. The main goal is to increase effectiveness.

The diagram is like on the picture, but components types are the following:
C1 - CBB22 564J 400V 0.56UF
C2 - 47mkF 63V
R1,R2 - 470kΩ SMD
LED - 8 serial SMD2835 LEDs
mains are 230V AC

Please disregard component types on the picture.

The circuit looks like:

 

[Gryd3]

Using a switch mode power supply for the LEDs will help. They are more complicated but are more efficient.
Using a resistor as a current limiting device will cause it to dissipate heat as wasted energy. This wasted power goes up considerably as you increase the voltage drop across it. (Usually caused by higher current, or needing to drop the supply voltage too far to match the LEDs)

 

[rafis]

Can I convert this board to switch mode power supply? Or can I modify resistors values to decrease heat dissipation?

 

[Gryd3]

Can I convert this board to switch mode power supply? Or can I modify resistors values to decrease heat dissipation?

You would need a different board layout. The typical power supply would be a 'buck' regulator that would be setup for constant current supply. They usually require additional support components. Any modifications to the existing board would result on a bunch of components hanging off the back.
And you can't change the resistor to dissipate less heat... The input voltage is constant, and so are the number of LEDs and the required current for them. These factors dictate your resistor.
Some may argue that you could add more LEDs to your module so that the resistor does not need to drop as much voltage across it. This is partially true. This would decrease the wasted power, but this reduces your safety margin for your LEDs and would allow for slight voltage variations to push too much current through your LEDs causing damage.

If I were you, I'd stick with the boards you have and if they bother you, sit down at your desk and with work out a replacement board that uses a different method to supply your LEDs.

 

[rafis]

I suppose, on this curcuit R1 and C1 give 100V. If I remove R1 and C1 and serial connect two bulbs on the mains 220V, will that work?

 

[KrisBlueNZ]

How did you determine that your circuit draws 9W?

 

[davenn]

I suppose, on this curcuit R1 and C1 give 100V. If I remove R1 and C1 and serial connect two bulbs on the mains 220V, will that work?

no, it will destroy them

 

[davenn]

Using a switch mode power supply for the LEDs will help. They are more complicated but are more efficient.
Using a resistor as a current limiting device will cause it to dissipate heat as wasted energy. This wasted power goes up considerably as you increase the voltage drop across it. (Usually caused by higher current, or needing to drop the supply voltage too far to match the LEDs)

I cant really see how a switchmode supply will be any more efficient in this case
the circuit is already directly converting 230VAC directly to DC for the LED's
adding a transformer and more components is only going to make it more inefficient

Rafis ...
As Kris asked ... How do you know they are using 9W ?



Dave

 

[rafis]

How did you determine that your circuit draws 9W?

Using a multimeter measured current and multiplied it on voltage. I have the larger bulbs that are even less effective (rated 3W and consume 17W).