Strobe controller on trailer?

Thread Starter

Matt J

Joined Dec 5, 2018
My first post so don't go to hard on me. I'm looking for something that would be installed on a trailer pulled behind a vehicle. I want to install strobes on the trailer for when I'm backing and or parked. There are remote RF transmitters and controllers that I have found that would work, but I want to try and utilize the hazards.
I need a device that would take the two 12v inputs from both brake lights/turn singles when the hazards are activated and then output 12v constant to a strobe controller. It would have to work off the pulse/flash of the hazard lights instead of the constant power when brakes are applied and both lights illuminate. Say the hazards are turned on and after a few flashes it would then turn on the 12v constant power output. Sometimes you pulse the brakes when stopping so I would want to try and avoid having it turn on if I pulsed the brakes by chance.


Joined Mar 14, 2008
How much current does the strobe controller input require?

Below is a circuit with LTspice simulation that should do what you want.
It uses a CD4093 quad Schmitt-trigger NAND gate package with a few diodes, resistors and capacitors.
The output stays low when no signal lights are on, both are steady on (braking) or only one turn-signal is on (green trace).
The output voltage (yellow trace) goes high only after both turn-signals (blue and green traces) are blinking together (hazards on) for at least 5 flashes.
The output goes back to zero about 9 seconds after the hazards are turned off

The CD4093 output can only deliver a few mA of current (load resistance no lower than about 2kΩ), so if the strobe signal needs more than that, a transistor buffer will need to be added.

The required Vdd power (pin 14) and ground connection (pin 7) to the CD4093 are not shown.

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