LED on a 1157 bulb circuit

[1-3-2-4]

I've been trying to figure this out.. the project is pretty simple.. If the headlight is off it's just a flash on and off..


However if the headlights are on since it's a dual filament it's a bright/dim flash.. I was going to retrofit some LED's in the front but I thought about how the LED driver would always keep it at the same brightness.. How could I get a bright/dim flash with the LED?

It's a car's circuit but I do have the wiring diagram if you need to see.

 

[carbonzit]

I have no idea what you mean: "If the headlight is off it's just a flash on and off".

Why don't you try explaining this again, this time more clearly? What happens when (e.g., "when the light switch is turned on, the lights flash on and off for a second", or whatever). Then someone can help you.

 

[DemonicSandwich]

I think he is referring to the taillamps of an automobile as they have two filaments.
One bright filament that is triggered by the brake and turn signal controls, and a dim one that comes on when the headlamps are switched on.

 

[carbonzit]

Could be. Why don't we wait for the O.P. to tell us what exactly they want?

 

[1-3-2-4]

I think he is referring to the taillamps of an automobile as they have two filaments.
One bright filament that is triggered by the brake and turn signal controls, and a dim one that comes on when the headlamps are switched on.

Yep this is what I'm talking about I could not think of a good way to put it without it sounding confusing.

 

[carbonzit]

So you're basically just asking how to drive a LED so that it appears either bright or dim?

The easy way is to use two different current-limiting resistors, one for bright (the one you'd normally use), the other one larger to somewhat "starve" the LED.

A better but more complicated way is to use PWM to drive the dim LED.

Either way, you'll have to experiment to come up with just the right "dim".

 

[1-3-2-4]

But the thing is at least looking at the LED driver here

https://www.electro-tech-online.com/custompdfs/2011/08/07021_07023_V22.pdf

2nd to last sheet they talk about using a resistor for fixed current reduction but I don't think that's going to get me what I want.

So to recap with just the headlights on and not flashing it should be dimmer then when it's flashing which somehow if I could bypass the limiter to get the full brightness that would be good.

 

[carbonzit]

How are you going to drive the LEDs? Are you trying to use the car's existing flashers? or will you be building your own circuit to do this?

 

[1-3-2-4]

I was going to use the car's flashers and try and use the driver in the PDF I listed if I can figure out the dimming part with the headlights on