I have a fender LED that has only one lead, and i need to make it possible for it to both light up when the headlights are on and also blink when the blinker is engaged.

I could see this going two ways:
1. marker is 50% brightness and it blinks to 100%... or
2. marker is 100% and it blinks OFF and ON

please advise

~andon

 

Assuming LED [D1 ] cathode is grounded and full brightness is 20 mA; head lamp [ H ] ground to 12 V.same with blink [B ]. Try a diode [D 2, D 3 ]resistor OR gate, H to anode D2,cathode to1200 Ω to D 1 ,same way with B. H on 50 %, H & B 50 %+50 % blink. Not tried.

 

How is the LED used now? A side marker light that's ON when the headlights are on, or as a turn signal iindicator?

 

What about...

+H---R------->|---------J--------led-------R------G

+B----------->|---------J

B=blinkers
H=headlights
J=junction
R=resistor
G=ground
--->|--- =diode

 

Do we know if there is a R from led to G ? As shown if H & B are hi , led will still be bright, only change will be whe both H & B are low. Help Sgt.

 

Sorry, It will work if either H or B is hi but not both high at the same .time.

 

 

I haven't seen a response from the OP to my question yet.
I'm really not willing to run off willy-nilly trying to come up with a solution if I don't know what the full problem statement is.

 

Sorry guys, I don't have internet at home for the moment...

Thank you for your responses!

I'm putting together a more specific question right now

thanks again

 

I'm using this accent light :
http://www.superbrightleds.com/specs/mcm.htm

MCM-A6 (Amber) 40mA @ 12V
it has 6 LED's

So i just need to allow that to function as both marker and blinker... thank you!

Externet : I am reading your posts now...

 

How is the LED used now? A side marker light that's ON when the headlights are on, or as a turn signal iindicator?

It's not hooked up as either at the moment.

 

I think we have enough info now. Go back to Externet 8-15 1:55 PM diagram. M ake R about 280 Ω s ;drop R & G from led cathode as it is already G. Should be enough contrast when both H & B are high to see a blink.

 

Well, it appears that the LED module has a built-in current limiting circuit. Attempting to use a simple resistor to limit current isn't going to work very well.

Seems to me that you will need to use some sort of PWM scheme. For 50% brightness, your PWM duty cycle will be 50%, and for full brightness, >99% duty cycle.

 

I built a module using the PIC12f675 to control my add on running light leds on my motorcycle. It powers up the running lights and blinks them off when the t/s is blinked on so that they blink alternately.

 

OK... so this is what i'm testing.
As i've said earlier, I'm using this accent light :
http://www.superbrightleds.com/specs/mcm.htm

MCM-A6 (Amber) 40mA @ 12V
it has 6 LED's
and has Resistors built in to limit the current to the circuit.

I just went to radioshack for some parts.

I purchased two 3A (200PIV) Rectifier Diodes LINK TO RADIOSHACK
and a package of 2.2kΩ Resistors LINK TO RADIOSHACK

This is my thinking...
12V
B+------>|(3A)----R1(2.2kΩ)-----X---LED(40mA)----|G
M+----- >|(3A)---------------------X

(where B+ is blinkers, M+ is markers, >| are 3A diodes, R1 is 2.2kΩ, X denotes a junction, LED is 40mA, and G is common ground)

Currently i have the LED + to my 2.2kΩ Resistor and then to 12V+ and the LED - to ground...
It's been hooked up for 15 minutes and does not appear to be getting hot at all... i can touch it and it feels like the temperature of the Resistor hasn't changed.

Ideally I want to have the most efficient and stable circuit possible as I would like to publish the solution to help others seeking to resolve this issue.

 

I built a module using the PIC12f675 to control my add on running light leds on my motorcycle. It powers up the running lights and blinks them off when the t/s is blinked on so that they blink alternately.

I would love to know more about this solution!

 

So... i'm thinking the 3A Diode is a bit overkill... I have also 75mA Diodes that would do just fine.

 

Any input would be greatly appreciated... For ease of construction i figured the axial diodes would fine... would a bridge rectifier be better?