n00b with a tail light query

[cantfindausername]

First off - HI

I've done a search on this but couldn't find anything that answered my question specifically.

I'm trying to construct some custom rear lights (like alot of other people I see on here), and I'm hitting problems.

This is what I want to happen

normal lights on....

**broken link removed**

brakes on....

**broken link removed**



The problem I'm having is that when I simulate normal lights on, all of the lights light up dim, not just the ones I want.

This is how they are currently wired up... (please excuse the shocking skill )

**broken link removed**

Thanks in advance for any advice offered... or comments on my skillz :lol:

Ant

 

[checkmate]

If you close the first switch, you can easily see that one of the paths for current flow could be as follow.
switch -> 1kohm -> 100ohm -> 100ohm -> 5leds -> gnd

Why not reorganise your switches. There's a master on-off switch, and another switch which is default-on to light up the centre cross?

 

[Nigel Goodwin]

You need two diodes to make an OR gate to feed the centre LED's, or even one would do - on the brake light side.

 

[eblc1388]

As per Nigel's suggestion.

 

[mstechca]

Modify the last circuit so that all resistances are more equal. Replace the 1K with a diode, andshort the 100 ohm before the diode already present. put a resistor between the point where two diodes meet and the string of lights. Now make all resistances the same value. Don't go lower than 100 ohms.

 

[MrMikey83]

Is this for a motorcycle or a car?
I replaced my cars tail light bulbs with store bought LED fittings and now my blinkers go super fast. I hope to someday get the entire taillight assembly from a junk car ('97 cougar), open them up and make a huge board of LED's over the entire red reflector part. Hmm, if I moved the license plate, I could put a huge scrolling message board accross the back of my car. Tell all those tailgaters what I think of them, lol.
~Mike

 

[zachtheterrible]

Why not just have the middle lights always on, connected to the 12v all the time, and the outer lights connected to the brake?

 

[eblc1388]

Modify the last circuit so that all resistances are more equal. Replace the 1K with a diode, andshort the 100 ohm before the diode already present. put a resistor between the point where two diodes meet and the string of lights. Now make all resistances the same value. Don't go lower than 100 ohms.

Thought you have spotted a mistake and doing it your way can save one resistor? :twisted:

The different resistor values are there for a good reason. If you don't get it, go out tonight and watch the brake light when the driver brakes.

 

[cantfindausername]

You need two diodes to make an OR gate to feed the centre LED's, or even one would do - on the brake light side.

Thanks for all the suggestions guys,

Nigel and eblc1388, from what I have read on various pages, your suggestion will be the first one I try as I believe this will give me the results I'm after.

Its for a car by the way.

Thanks again,
Ant

 

[SkinnyBoy]

Modify the last circuit so that all resistances are more equal. Replace the 1K with a diode, andshort the 100 <a href="#">ohm</a> before the diode already present. put a resistor between the point where two diodes meet and the string of lights. Now make all resistances the same value. Don't go lower than 100 ohms.

Thought you have spotted a mistake and doing it your way can save one resistor? :twisted:

The different resistor values are there for a good reason. If you don't get it, go out tonight and watch the brake light when the driver brakes.

yes, but he's got 1/4 the LED's for the tail light so that its duller than the brake lights, he doesn't need to make the LED's dimmer aswell...

 

[cantfindausername]

Out of interest, can anyone supply a product code or something for a diode that I would need?

Thanks
Ant

 

[Nigel Goodwin]

Out of interest, can anyone supply a product code or something for a diode that I would need?

Any small rectifier diode, something like a 1N4001 or a BY127, just ask for a 1A rectifer diode.

 

[cantfindausername]

Thanks very much.