LED driver without IC and Transformer

[Arshid KV]

I think to make LED lamps commercially. So I got circuit for it. But resisters are heating.
What is the power conception in this circuit ?
Please help me..

 

[jiripolivka]

Your circuit is correct and can function but the 470k resistor must dissipate 1W so it must get hot.
Your experience explains why others use transformers and PWM ICs to feed LEDs with pulsed current, all that to save on power dissipation.

 

[Arshid KV]

Price of the lamp will increase. I think to make very cheap lamp. Can I use above circuit for making 8 watt LED lamp ( 6 LEDs) ?

 

[KlausST]

Hi,

the 470k resistor dissipates less than 0.1W. Heating is minimal.

the whole concept is designed for low power dissipation.
The usual current limiting resistors are replaced by current limitng Cs. 3 x 1uF generate an xc of about 1060 Ohms at 50Hz.
for an estimation: the current is limited to about 210mA. (This could fit to the 1W LED lamp)
The Cs generate reactive power, but no heating.

But...if my calcualtions are right, then in every 100R resistor there is a power dissipation of 0.21A x 0.21A x 100 Ohms = 4.4W. Here therated 1W will blow.

I doubt if there is a need for the 10R resistor, because the limiting happens with the 100R resistor.

But as long as there are no data for the LED one can not calculate the devices values.

Klaus

 

[yassin.kraouch]

I think to make LED lamps commercially. So I got circuit for it. But resisters are heating.
What is the power conception in this circuit ?
Please help me..
View attachment 108057

you have to be careful here, there is no isolation from mains, the power factor of this circuit wil lbe low, you have to think where your product will be sold,
its better to change the R1 resistor to 1meg ohm, because the role of this cap is only to discharge the film cap,

 

[Arshid KV]

How to improve power factor ?

 

[KlausST]

Hi,

How to improve power factor ?

Why?
Improving power factor will not improve efficiency.

Klaus

 

[Arshid KV]

sorry... how to improve efficiency?

 

[Audioguru]

sorry... how to improve efficiency?

Use a transformer.

 

[Arshid KV]

But transformer increase size and cost

 

[yassin.kraouch]

Hi,



Why?


Klaus

if his product will be sold in a coutry a power factor requirement than its mandatory to increase the power factor,
the efficieny of this kind of driver is good, and if you optimize your circuit you can reach 90%,

 

[Arshid KV]

Please help me, How to optimize ?

 

[yassin.kraouch]

Please help me, How to optimize ?

the only solution you can implement here, is to increase the voltage of the LED strig, i mean use more LEDs in series, in this case you will have good enought power factor, but normally in other circuit they add a valley fill circuit which help a little bit to increase the power factor

 

[Arshid KV]

My resisters are heating . How to solve ?
How to calculate power factor ?

 

[Audioguru]

Price of the lamp will increase. I think to make very cheap lamp.
But transformer increase size and cost

Does anybody sell an LED lamp that uses only 1W? Most are 3W to 15W.

Why do you talk about cost and cheap? LED lamps are very expensive.
When you make lamps, don't you need to pay a high fee to have them certified to be safe?

Buy an LED lamp like you want to make and take it apart to see how it is made.

 

[Arshid KV]

Sir, I think to make 5 watt LED lamp. I know LED lamps have high price. So I introducing this type of circuit. Can you help me ?