Help with simple project

[beerdrinker1]

Hello this is my first post in your forum and I appreciate your help to design/ create a simple project.
The ideia is build two auxiliary braking light's to my motorcycle topcase.

My idea is to have both leds lighted up at about 50% of their power as rear running light and at full power when the brakes are activated.

Alternator info: 14 V/310 W at 5,000 r/min
I will use: 2 X 10W LED chip
LED Specifications: Voltage: 9V-12V; Forward Voltage: 10V; Power: 10w; Forward Current: 1000mA

How do I switch from running to brake lights? Just occured me a relay. .Is ther any other whay? I Need a simple, reliable and compact scheme for this.

I stop studing electronics at about 15 years ago, so my knowledge is almost gone.

Thank you in advanced for your help!

 

[alec_t]

Is there any other way?

Yes. You could use a PWM method (which would be more power-efficient than a series resistor switched in with a relay).

Edit: BTW, you might need to use less than 50% power for the running lights, to provide sufficient perceived brightness difference between those and the brake lights.

 

[crutschow]

The easiest would be to use a 12V SPDT relay with the coil controlled by the brake switch and a power resistor in series with the running position. You might have to experiment to get the correct resistor size -- try 6Ω, 10W to start.

If you want more efficiency you could try a PWM module such as one of these for the running light position.

I assume you don't need the turn-signals integrated into these lights(?).

 

[Joe G]

https://www.google.com/imgres?imgur...JomVUeLUH7av4AOS0oDgDw&ved=0CDAQ9QEwAA&dur=65 has a 2 transistor arrangment that works decently after adjusting the resistors. Its been on this forum a few times over the years. and has been modified/adjusted from the original design I posted.

 

[beerdrinker]

The easiest would be to use a 12V SPDT relay with the coil controlled by the brake switch and a power resistor in series with the running position. You might have to experiment to get the correct resistor size -- try 6Ω, 10W to start.

If you want more efficiency you could try a PWM module such as one of these for the running light position.

I assume you don't need the turn-signals integrated into these lights(?).

Hello, thank you for your answer,
The relay was my first, and only, idea. Maybe I stick with it since it is reliable.
Sorry the ignorace but what does the PWM does?
No, I don´t need the turn signals.
Thank you

EDIT

I think I got it, PWM I can adjust the brightness I want without the need of changing resistors, it's that it?

 

[Joe G]

Yep. pwm would turn on/off really fast making the led appear to be dimmer ,;50% duty cycle would make the led appear to be half as bright then 100%, give or take. some of the newer cars on the road use pwm on their brake lights, they appear to be pulsing really fast,. you might not of noticed if you're not aware of it though.

 

[Diver300]

https://www.google.com/imgres?imgur...JomVUeLUH7av4AOS0oDgDw&ved=0CDAQ9QEwAA&dur=65 has a 2 transistor arrangment that works decently after adjusting the resistors. Its been on this forum a few times over the years.

I would suggest that you have circuits that have a resistor in each set of LEDs to keep the current in balance in each set.

Also, PWM dimming should be at 500 Hz or faster if it isn't to be visible. Where there is movement, such as on a vehicle, PWM at lower frequencies can be visible, but that does depend on the lots of factors, and some people are more sensitive to it than others.

 

[gareng]

uniqe brake lamp

How about this funny brake lamp **broken link removed**