LED driver without IC and Transformer

[Arshid]

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..

 

[(*steve*)]

Sure, current through resistors will cause them to heat. Which resistors are heating, what power rating do they have, and how hot are they getting?

 

[Arshid]

R2 and R3 is heating . R2 and R3 are 1 watt.
My doubt is , Can I build 7 watt LED lamp (6 LEDs) from above circuit ?

 

[(*steve*)]

What is the voltage across R3 and R4?

Yes, I realize R4 isn't getting hot.

And don't kill yourself taking these measurements -- your entire circuit is at mains potential.

 

[Arshid]

1 watt LED voltage rating is 3.6V. and 200mA.

 

[(*steve*)]

My nipples explode with delight

 

[KrisBlueNZ]

And your hovercraft is full of eels. Steve, WHAT have you been smoking? LOL

 

[(*steve*)]

It was either that or repeat the question.

Ni!

 

[KrisBlueNZ]

Arshid, can you measure the AC voltage across R3 and the DC voltage across R4?

Also, upload a photo of your circuit.

 

[(*steve*)]

Both should be DC Kris.

 

[KrisBlueNZ]

Sorry, I meant to say the AC voltage across R2 and the DC voltage across R3.

 

[Arshid]

R4 is 230mv and R3 is 21V.

 

[KrisBlueNZ]

OK Arshid. Now, the photograph?

 

[Arshid]

AC volt in R2 is 21V. DC volt in R3 is 21V.

 

[Arshid]

file

 

[(*steve*)]

R4 is 230mv and R3 is 21V.

OK, so that means that you have 23mA going through the LED (that's less than 1/10W for that LED), and 187mA through the zener diode (which I'm assuming is getting pretty hot).

Removing the zener diode will probably give you about 1W through the LED (it will be a little lower, but not so much).

Currently, for an output of less than 0.1W, your zener is dissipating about 0.75W, your 100 ohm resistors about 4.5W each.

So, ignoring other losses (and there are several) you are wasting about 9.75W to dissipate 0.1W in the LED. So the circuit is almost exactly 1% efficient.

With this circuit, you'd be better off with an incandescent bulb.

Now, you want to up the power to 7W? Do you mean 0.7W with 70W wasted, or 7W with 700W wasted?

 

[Arshid]

How to make good efficient circuit (to sold commercially ) ?

 

[Arshid]

Please note that LED rated 3.3V and 200mA.

 

[KrisBlueNZ]

How to make good efficient circuit (to sold commercially ) ?

Look inside a commercially manufactured LED lamp! That will answer that question.

 

[(*steve*)]

How to make good efficient circuit (to sold commercially ) ?

Well, you'll probably need an inductor and some active electronics (yes, maybe an IC).

There's a reason that apparently complex electronics are used.