Help me about this LED driver works

[mbajing_deh]

As title says



this is from scooter headlamp
selectable for low beam (mode 1) and high beam (mode 2)

i'm confuse how this thing works

Best Regards

 

[D.A.(Tony)Stewart]

As title says

View attachment 113075

this is from scooter headlamp
selectable for low beam (mode 1) and high beam (mode 2)

i'm confuse how this thing works

Best Regards

Certainly leaves a lot to the imagination with missing info.

possibly it uses Vbat/2 to drive the LED Array from the bottom left at Vbat or Ggnd and low beam is reflected differently and driven at lower power with I having a diode drop to reduce current.

The SCR acts as overvoltage protection to the LEDs and must be designed to shutoff by having a large holding current.

 

[mbajing_deh]

Oh i forgot, this is PCB silkscreen marking for those 5 connetor

 

[mbajing_deh]

Certainly leaves a lot to the imagination with missing info.

possibly it uses Vbat/2 to drive the LED Array from the bottom left at Vbat or Ggnd and low beam is reflected differently and driven at lower power with I having a diode drop to reduce current.

The SCR acts as overvoltage protection to the LEDs and must be designed to shutoff by having a large holding current.

Thank you for reply

I think V bat have a "wide range" voltage (commonly about 12-14.5V)
to drive them with 1/2 Vbat ?

How about AC or DC Halfwave feeding this circuit? because when SCR on, its remain on with "pure DC" right ?
many scooter have this configuration for headlamp (but using halogen lamp)

Best Regards

 

[kam1787]

I would have to see more of the circuit. There are 'headlight' LEDs in mode 1 but not in mode 2?

Vbat does have a wide range; around/less than 11V to 15V

1/2 Vbat could work - depends on the rest of circuit.

It does appear like there is AC.

yes, the SCR would remain on if the voltage was pure DC

 

[mbajing_deh]

This is the whole board, i doubt about external circuit to drive those led exist.
its "cheap scooter" not car LED that usually have buck/bost LED driver



Those red circle is to drive main LED
2 for lowbam and other 2 is on at high beam (total 4 led on)

Those Blue circle is only drive DRL LED, i have check PCB not connected to anything

p.s
its broken anyway, LED, Zener, and SCR is gone
my friend try to feed this circuit with 27VDC

 

[kam1787]

Thanks for the photo, but I was after a complete circuit diagram, showing the switches, load[LEDs], and electronics.

 

[chuckey]

On small motor bikes, the nightime lights all run off AC. The DC is for turn indicators and brake lights, horn ans perhaps the ignition.
Frank