Separate Brake Light From Turn Signal

eTech said:

Resolving this makes a
solution more complicated. Detecting the state of static switches, like a
turn signal switch, or brake switch, is much simpler, but isn't useful for
the solution you want.

Click to expand...

Awe man.
I did learn a bunch and for that i am thankful. Do you feel that the circuit member crutschow designed is viable? It is not that I doubt the design but there was a bit of confusion in the beginning as to how the circuit was to function. He indicated in post #42 the following which seems to be a problem that his circuit solves.

Crutschow said:
"It's not clear to me that any of the other circuits posted here operate properly for the combined signals of one side blinking and the other side steady-on, indicating a combined turn and braking situation.
Below is the LTspice sim of one that does:"

Your thoughts.

Only way to know is if all states are checked.
Another state to look out for is when removing brake, the third light delays a half cycle.
It should also handle the "emergency" state where both lights are flashing.

Just a heads up, the simulation can be misleading..

ThomsCircuit said:

Awe man.
I did learn a bunch and for that i am thankful. Do you feel that the circuit member crutschow designed is viable? It is not that I doubt the design but there was a bit of confusion in the beginning as to how the circuit was to function. He indicated in post #42 the following which seems to be a problem that his circuit solves.

Crutschow said:
"It's not clear to me that any of the other circuits posted here operate properly for the combined signals of one side blinking and the other side steady-on, indicating a combined turn and braking situation.
Below is the LTspice sim of one that does:"

Your thoughts.

Click to expand...

Crutschow's circuit uses a latch, which may or may not be ok. I thought about using a latch of some type in my circuit, but was concerned with a circuit failure causing the 3rd brake light to suddenly latch "on". Another thing that concerns me with this whole idea is the possibility of a circuit failure causing the brake light to suddenly come on, and, in turn, causing an emergency application of the brakes by a following vehicle (potentially causing an accident). Please advise.

crutschow said:

Here's the circuit powered from the turn-signal lights:
(The delay circuit causes an occasional extra brake pulse when the braking ends, such as at the 14s time in the sim, but that shouldn't be a problem to those following the vehicle.)

Do you know how much current the brake light takes?
That will determine the required current rating of the diodes.
(The diodes shown are 3A).

View attachment 145878

Click to expand...

Hi Crutschow,

I'd like to play with this circuit. I can redraw it in LTspice, but I'd rather just use a copy of your .asc file. Can you post the .asc please?