Logic circuit third brake light.

[Tricky]

Does anyone know what the circuit look's like for the 3 Brake Light Module?. It Prevents brake light from flashing with turn signal, is on. When the brake is
on the 3 brake light is on. When the turn light is on, or toggling, the 3 brake light is not toggling or flashing.

So you hook into the (right turn/brake light) wire. Go into the Module and to the 3 brake light. With out the Module, the 3 Brake light would be flashing or toggling when the Right turn light is on.

here is link

https://auto.sears.com/LOGIC-CIRCUIT/Product.htm?catalogId=10623&N=600024691&productId=2003583

 

[Thunderchild]

err, maybe it's a third light that comes on with the left and right brake lights, i think you need to better explain what you are asking

 

[crutschow]

He's referring to a car where the brake light doubles as the turn-signal light. So the module keeps the 3rd light from blinking when one of the turn signals is on.

I would think that could be simply accomplished by using a diode from each brake/turn-signal light to the 3rd light. That way the brake light that's not flashing would provide steady power to the 3rd light.

 

[Tricky]

Why then do they call it A Logic circuit?
The one you can get at Sears and is
there away you could do it the other way.
When tagging, 3 brake light would be tagging too.

 

[crutschow]

Sorry, I don't understand your question.

 

[Tricky]

Why then do they call it A Logic circuit?
How do they do it with Logic Circuit?
The 3 brake light modual, I am talking about.

Is there away you could do it the other way around. With Logic Circuit?
When tagging, 3 brake light would be tagging too.

Why then do they call it A Logic circuit?
How do they do it with Logic Circuit?
The 3 brake light modual, I am talking about.

Is there away you could do it the other way around. With Logic Circuit?
When tagging, 3 brake light would be tagging too.

 

[PatM]

Sounds like it uses a AND gate to detect when both brake lights are on.

 

[adamey]

AND gate wouldn't work properly either. If you are turning left and braking, then the left light flashes but right light is steady for brake, so your third would flash too with an AND gate.

I'm not sure of an easy way to do this at the rear of the vehicle with only access to the two wires for L/R bulbs without using some kind of circuit to detect when one of the two inputs is solid (braking).

Simplest would be to tap into the brake switch and use that output to directly power third brake light. In vehicles with single bulbs for turn/brake, the turn signal switch also has a brake input and when turning allows the brake input to travel to the opposite bulb to turn it on. Essentialy, the turn signal switch has the "logic" as to which bulbs get turned on.

 

[crutschow]

I realize that the diodes I suggested won't work either, since obviously a single turn-signal will then cause the 3rd light to blink.

You could use a flip-flop circuit that would operate the 3rd light when both stop lights are on, and then doesn't turn it off until both lights are off. For example, an AND gate to SET the flip-flop and a NOR gate to RESET the flip-flop. (Or since some FF SET and RESET are active low, use a NAND gate for the SET, and an OR gate for the RESET). That way the 3rd light will still stay steady on when the brake light is maintaining one light on and the other light blinking, but stays off when the brakes are off and either light is blinking.

 

[Tricky]

Something like this, but I can't get the circuit to work. I have put it on the Attachments.

 

[mneary]

I can't follow the logic, but what little I can understand it appears that it requires the brake and blinker to be able to sink as well as source current. In a real automobile circuit this won't happen.

 

[adamey]

^ In this example maybe not, but I can think of many other examples in automobiles where a circuit will sink OR source current in different circumstances.

 

[crutschow]

I can't follow the logic, but what little I can understand it appears that it requires the brake and blinker to be able to sink as well as source current. In a real automobile circuit this won't happen.

The bulb connected to ground will sink current. Incandescent bulbs are a low impedance when cold. It could be a problem, however, if the bulbs are LEDs.

 

[audioguru]

Isn't it illegal for a car to blink a brake light instead of a separate turn signal light?
What happens when the car has its emergency flasher turned on? Then no brake lights? Its stupid.

Aren't brake lights red and turn signal lights orange?

 

[Hero999]

This is probably in some 3rd wrold country where no one cares and if you do get stopped you can bribe the copper.

 

[crutschow]

I do remember some old U.S. cars that shared a light for the brake and turn-signal. Saved a wire and two bulbs. Of course the turn-signal color was thus also red. According to Wikipedia, red rear turn-signals are still legal in North America. Don't know whether sharing still is.

 

[Tricky]

Go to this web site And check it out. I am from the USA,


**broken link removed**

 

[audioguru]

Go to this web site And check it out. I am from the USA,


**broken link removed**

This Canadian circuit does not say if the turn signals and the brake lights are the same.
I think they are separate.

 

[Wade Hassler]

That circuit lights the 3rd light only when both inputs are on.
If the inputs were brake-light-only, there would be no need of the circuit: it could be replaced by two diodes

 

[audioguru]

I have never seen a car with the turn signal light the same as the brake light. They are always separate.