Hello, I'm looking AC230 to 120mA 17V MAX CC LED driver circuit without flicker.

https://www.aliexpress.com/item/4000473379678.html
This lists minimum voltage at 30V, will it now work lower?

 

Hello, I'm looking AC230 to 120mA 17V MAX CC LED driver circuit without flicker.

https://www.aliexpress.com/item/4000473379678.html
This lists minimum voltage at 30V, will it now work lower?

I would assume no, based on the “specifications”. They show 30V as a minimum and I have to assume there’s a reason, otherwise they’d cite a lower number.

 

So any hacking possible to lower the voltage?
I'm having hard time finding needed power supply.

 

Factory specs on bulb:

3.5W
37mA

Measured specs with OEM PSU:

4.4W
32mA
128V

7Leds = 1Led => 32mA and 18.28V


Desired PSU

AC 230V to ~18V CC PSU autoranging and at 20-25mA all leds in parallel

 

I hsve this PSU that uses JW1992M CC driver, the output current with connected LED's that are parallel is

14/15mA
13.5/14.2V

http://www.icdemi.com/manual/JW1992C.pdf

My PSU looks like this, but short circuit curent is 118mA
https://www.alibaba.com/product-det...pm=a2700.7724857.normalList.12.786f7fe1mVUTOl

I see I need to repalce the Current sense resistor and will have more current/voltage? But how to calculate it the datasheet is unclear, there is soldered 1R5 current sense resistor in PSU.

My question what to replace it with?

 

1: In the data sheet there is a "max" current based on how big the internal MOSFET is. There are versions of output MOSFET W, A, B ,C, D and how much current max. Do not get near the max current for the part in your board.

2: I can not find "Vref" so the formula will not work. But it is clear the current is related to 1/Resistor. So if you want 2x the current the resistor needs to be 1/2.
It looks like 0.8 ohms = 250mA based from information in post #5.

 

Thank you or your input.

I used 4.7ohm and 1ohm resistor to make 0.8ohm

Now I get this output on my leds:
14.6V
36mA

It's interesting as I first tried 1.2ohm resistor and I got 15V 14.23mA
With 0.8Ohm I get 14.6V 36mA it's alittle low on the voltage for some reason, but miliamps are spot on.
My version is M

Any suggestions?

 

My version is M

Lowest current version.

With 0.8Ohm I get 14.6V 36mA it's alittle low on the voltage for some reason, but miliamps are spot on.

Good. The voltage is a little unpredictable. It changes with temperature and from one batch of LEDs to another. If you have the right current that is most important.

 

I connected whole string of leds 7 total, and I don't know why but voltage is the same 14.6V but current is 36mA !
Why? Should be 36 x 7 = 252mA or at least 118mA ( short circuit curent is 118mA ).

Any ideas?

 

I connected whole string of leds 7 total, and I don't know why but voltage is the same 14.6V but current is 36mA !
Why? Should be 36 x 7 = 252mA or at least 118mA ( short circuit curent is 118mA ).

Any ideas?

Series or parallel? How are you measuring current?

 

Leds are connected in Parallel current measured by uni-t ut210e clamp on 2A mode on one of the wires to leds.

 

I connected whole string of leds 7 total, and I don't know why but voltage is the same 14.6V but current is 36mA !
Why? Should be 36 x 7 = 252mA or at least 118mA ( short circuit curent is 118mA ).

I do not understand exactly what you are doing but:
I think you chose a resistor for 36mA. With one set of LEDs you get 36mA. With two sets of LEDs you should get 36mA total. With 3 set of LEDs you will get 36mA etc..... You built a 36mA power supply. It will make 36mA. It will not make 252mA.

 

Leds are connected in Parallel current measured by uni-t ut210e clamp on 2A mode on one of the wires to leds.

Parallel is not a good idea unless you use load-balancing resistors. Otherwise one string will draw a little more, get hotter and draw still more, and potentially overload.